Maternal vascular indices at 36 weeks' gestation in small and growth restricted fetuses

OBJECTIVE

To compare maternal vascular indices and hemodynamic parameters at 35-37 weeks' gestation, in pregnancies complicated by small for gestational age (SGA) fetuses and those with fetal growth restriction (FGR).

METHODS

This was a prospective observational non-intervention study in women with singleton pregnancies attending for a routine hospital visit at 35+0 to 36+6 weeks' gestation. The visit included recording of maternal demographic characteristics and medical history, vascular indices and hemodynamic parameters obtained by a non-invasive operator independent device, including pulse wave velocity, augmention index, cardiac output, stroke volume, central systolic and diastolic blood pressure, total peripheral resistance and fetal heart rate. Hypertensive disorders of pregnancy were excluded and the values in the SGA and FGR groups were compared between them and with unaffected pregnancies. Diagnosis of SGA was based on the birth of a baby with birthweight below the 10th percentile for gestational age. In FGR, in addition to a birthweight below the 10th percentile, at the 35-37 weeks scan Doppler studies had shown that the uterine artery or umbilical artery pulsatility index (PI) was above the 95th percentile for gestational age or the fetal middle cerebral artery PI was below the 5th percentile.

RESULTS

In the 6,413 women included in the study there were 605 (9.4%) cases of SGA, 133 (2.1%) of FGR and 5,675 (88.5%) unaffected by SGA or FGR. Women with SGA or FGR, compared to unaffected pregnancies, had increased peripheral vascular resistance and reduced cardiac output. Central systolic and diastolic blood pressure were also increased, whereas aortic stiffness assessed by pulse wave velocity and augmentation index did not differ between affected and unaffected pregnancies. In the FGR, compared to the SGA group, central systolic and diastolic blood pressure were higher, whereas, heart rate was lower.

CONCLUSIONS

In SGA and FGR pregnancies there are deranged maternal hemodynamic responses when these are compared to normal pregnancies. Mothers with FGR babies have higher central blood pressure compared to SGA ones, but it remains unclear whether these differences are driven by the size of the fetus or pathological fetal growth. This article is protected by copyright. All rights reserved.

Comparison of competing-risks model with angiogenic factors in midgestation screening for preterm growth-related neonatal morbidity

OBJECTIVES

First, to evaluate the predictive performance for preterm growth-related neonatal morbidity of a high soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio or low PlGF at midgestation and, second, to compare the performance of a high sFlt-1/PlGF ratio or low PlGF with that of the competing-risks model for small-for-gestational age (SGA), utilizing a combination of maternal risk factors, sonographic estimated fetal weight and uterine artery pulsatility index.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 19-24 weeks' gestation in two maternity hospitals in England. The visit included recording of maternal demographic characteristics and medical history, carrying out an ultrasound scan and measuring serum PlGF and sFlt-1. The primary outcome was delivery < 32 and < 37 weeks' gestation of a SGA neonate with birth weight < 10th or < 3rd percentile, combined with neonatal unit (NNU) admission for ≥ 48 h or a composite of major neonatal morbidity. The detection rates in screening by PlGF < 10th percentile, sFlt-1/PlGF ratio > 90th percentile and the competing-risks model for SGA were estimated and then compared using McNemar's test.

RESULTS

In the study population of 40 241 women, prediction of preterm growth-related neonatal morbidity provided by the competing-risks model for SGA was superior to that of screening by low PlGF concentration or high sFlt-1/PlGF ratio. For example, at a screen-positive rate of 10.0%, as defined by the sFlt-1/PlGF ratio > 90th percentile, the competing-risks model predicted 70.1% (95% CI, 61.0-79.2%) of SGA < 10th percentile and 76.9% (95% CI, 67.6-86.3%) of SGA < 3rd percentile with NNU admission for ≥ 48 h delivered < 32 weeks' gestation. The respective values for SGA with major neonatal morbidity were 73.8% (95% CI, 64.4-83.2%) and 77.9% (95% CI, 68.0-87.8%). These were significantly higher than the respective values of 35.1% (95% CI, 25.6-44.6%), 35.9% (95% CI, 25.3-46.5%), 38.1% (95% CI, 27.7-48.5%) and 39.7% (95% CI, 28.1-51.3%) achieved by the application of the sFlt-1/PlGF ratio > 90th percentile (all P < 0.0001).

CONCLUSION

At midgestation, the prediction of growth-related neonatal morbidity by the competing-risks model for SGA is superior to that of a high sFlt-1/PlGF ratio or low PlGF. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Evaluation of angiogenic factors in prediction of growth-related neonatal morbidity at term and comparison with competing-risks model

OBJECTIVES

First, to describe the distribution of biomarkers of impaired placentation in small-for-gestational-age (SGA) pregnancies with neonatal morbidity; second, to examine the predictive performance for growth-related neonatal morbidity of a high soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio or low PlGF; and, third, to compare the performance of a high sFlt-1/PlGF ratio or low PlGF with that of the competing-risks model for SGA in predicting growth-related neonatal morbidity.

METHODS

This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation in two maternity hospitals in England. The visit included recording of maternal demographic characteristics and medical history, an ultrasound scan and measurement of serum PlGF and sFlt-1. The primary outcome was delivery within 4 weeks after assessment and at < 42 weeks' gestation of a SGA neonate with birth weight < 10th or < 3rd percentile, combined with neonatal unit (NNU) admission for ≥ 48 h or a composite of major neonatal morbidity. The detection rates in screening by PlGF < 10th percentile, sFlt-1/PlGF ratio > 90th percentile, sFlt-1/PlGF ratio > 38 and the competing-risks model for SGA, using combinations of maternal risk factors and Z-scores of estimated fetal weight (EFW) with multiples of the median values of uterine artery pulsatility index, PlGF and sFlt-1, were estimated. The detection rates by the different methods of screening were compared using McNemar's test.

RESULTS

In the study population of 29 035 women, prediction of growth-related neonatal morbidity at term provided by the competing-risks model was superior to that of screening by low PlGF concentration or a high sFlt-1/PlGF concentration ratio. For example, at a screen-positive rate (SPR) of 13.1%, as defined by the sFlt-1/PlGF ratio > 38, the competing-risks model using maternal risk factors and EFW predicted 77.5% (95% CI, 71.7-83.3%) of SGA < 10th percentile and 89.3% (95% CI, 83.7-94.8%) of SGA < 3rd percentile with NNU admission for ≥ 48 h delivered within 4 weeks after assessment. The respective values for SGA with major neonatal morbidity were 71.4% (95% CI, 56.5-86.4%) and 90.0% (95% CI, 76.9-100%). These were significantly higher than the respective values of 41.0% (95% CI, 34.2-47.8%) (P < 0.0001), 48.8% (95% CI, 39.9-57.7%) (P < 0.0001), 37.1% (95% CI, 21.1-53.2%) (P = 0.003) and 55.0% (95% CI, 33.2-76.8%) (P = 0.035) achieved by the application of the sFlt-1/PlGF ratio > 38. At a SPR of 10.0%, as defined by PlGF < 10th percentile, the competing-risks model using maternal factors and EFW predicted 71.5% (95% CI, 65.2-77.8%) of SGA < 10th percentile and 84.3% (95% CI, 77.8-90.8%) of SGA < 3rd percentile with NNU admission for ≥ 48 h delivered within 4 weeks after assessment. The respective values for SGA with major neonatal morbidity were 68.6% (95% CI, 53.1-83.9%) and 85.0% (95% CI, 69.4-100%). These were significantly higher than the respective values of 36.5% (95% CI, 29.8-43.2%) (P < 0.0001), 46.3% (95% CI, 37.4-55.2%) (P < 0.0001), 37.1% (95% CI, 21.1-53.2%) (P = 0.003) and 55.0% (95% CI, 33.2-76.8%) (P = 0.021) achieved by the application of PlGF < 10th percentile.

CONCLUSION

At 36 weeks' gestation, the prediction of growth-related neonatal morbidity by the competing-risks model for SGA, using maternal risk factors and EFW, is superior to that of a high sFlt-1/PlGF ratio or low PlGF. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

First trimester screening identifies maternal cardiac maladaptation at mid-gestation

BACKGROUND

First, a logistic regression model, based on maternal demographic characteristics and medical history and blood pressure at 11-13 weeks' gestation, can identify about 70% of women who develop future chronic hypertension (CH) in the three years following pregnancy, at screen positive rate of 10%. Second, at mid-gestation women who subsequently develop hypertensive disorders of pregnancy (HDP) have increased peripheral vascular resistance and mild cardiac functional and morphological alterations and these cardiovascular abnormalities persist for at least 2 years after delivery.

OBJECTIVE

To examine whether the use of the first-trimester risk for subsequent development of CH can help to identify women at high risk for cardiovascular maladaptation at mid-gestation.

METHODS

Prospective observational study in 3812 women with singleton pregnancies women attending for a routine hospital visit at 11+0 to 13+6 weeks' gestation and again at 19+1 to 23+3 weeks at King's College Hospital, London, UK between August 2019 and August 2020. The first-trimester visit included recording of maternal demographic characteristics and medical history and measurement of systolic and diastolic blood pressure. At mid-gestation detailed maternal cardiovascular assessment was carried out. The association of risk for development of CH, determined from first-trimester assessment, and cardiovascular indices at mid-gestation was examined.

RESULTS

Women who are at high-risk for development of future CH, compared to those at low-risk, had a higher incidence of hypertensive disorders of pregnancy (HDP). In addition, high-risk women, had reduced systolic and diastolic function at mid-gestation. Among women with HDP, those who were high-risk for future CH, compared to those at low-risk, also had worse cardiac function at mid-gestation.

CONCLUSION

Use of a model for first-trimester prediction of subsequent development of CH can identify women who show evidence of cardiac maladaptation at mid-gestation. Further studies are needed to clarify whether women who screen as high-risk for future CH, compared to those at low-risk, have reduced cardiac function beyond pregnancy. This article is protected by copyright. All rights reserved.

Long-term cardiovascular assessment of women who had a pregnancy complicated by a hypertensive disorder

BACKGROUND

Women with hypertensive disorders of pregnancy (HDP) are at increased risk of developing hypertension and cardiovascular disease later in life. However, from studies so far, it is difficult to define whether this association reflects preexisting maternal cardiovascular risk or merely reflect a potentially causal relationship between HDP and later cardiovascular risk.

OBJECTIVES

We performed detailed cardiovascular assessment in women at mid-gestation, prior to development of a HDP and at 2 years post-partum aiming to identify cardiovascular changes prior to development of HDP and to assess persistent cardiovascular alterations long after the HDP event.

METHODS

This was a prospective observational study in which we performed detailed cardiovascular assessment at mid-gestation and at median of 2.3 years (interquartile range 2.1 to 2.4 years) post-partum. We examined 112 women who developed a HDP and 451 women whose pregnancy was not complicated by hypertension. We used conventional and more advanced echocardiographic techniques, i.e. speckle tracking, to accurately determine left ventricular systolic and diastolic function. We used M-mode measurements to determine left ventricular remodeling and estimate left ventricular mass. Maternal vascular status was assessed using ophthalmic artery Doppler and by calculating peak systolic velocity (PSV) ratio, as a marker of peripheral vascular resistance.

RESULTS

At mid-gestation, women who subsequently developed HDP had increased ophthalmic artery PSV ratio. These women also had mild cardiac functional and morphological alterations which were mostly accounted for by maternal cardiovascular risk factors. At 2 years post-partum, women who experienced HDP, compared to those who did not, had cardiovascular abnormalities with reduction in left ventricular systolic and diastolic function which remained after multivariable analysis. Longitudinal analysis demonstrated that the evolution of cardiovascular changes in the HDP and non-HDP groups was similar.

CONCLUSION

Mild cardiac functional and morphological alterations precede the development of HDP and such changes persist for at least 2 years postpartum. The cardiac changes are likely to be the consequence of preexisting maternal cardiovascular risk factors rather than an adverse consequence of HDP. This article is protected by copyright. All rights reserved.

Impact of hypertensive disorders of pregnancy on offspring cardiovascular function. Study from fetal life to early childhood

OBJECTIVE

Epidemiological studies suggest that children following in utero exposure to hypertensive disorders of pregnancy (HDP) may be at increased long term cardiovascular risk. However, data in early childhood are lacking. We aimed to investigate the independent influence of HDP on childhood heart after accounting for differences in childhood risk factor profile.

METHODS

We performed detailed cardiovascular assessment in fetuses at mid-gestation and at a median of 2.3 years (IQR: 2.1, 2.4 years) postnatally in 71 cases where the mothers had HDP and 304 who did not have HDP.

RESULTS

There were no differences in demographic characteristics between groups but in the HDP group delivery was earlier and birthweight was lower. In fetal life, there were no significant differences in cardiac function or structure between the HDP and non-HDP groups. In early childhood, in the HDP compared to the non-HDP group, there was greater relative wall thickness (0.7 SD 0.3 vs. 0.6 SD 0.3 mm, p=0.047) and increased left ventricular mass (80.9 SD 20.4 vs. 75.7 SD 16.5, p=0.024); however, these differences were abolished following multivariable analysis. Longitudinal analysis revealed that in HDP, compared to the non-HDP group, there was no difference in the change of cardiac functional indices from fetal life to early childhood.

CONCLUSION

Epidemiological studies suggest that HDP have an adverse impact on offspring cardiovascular health, but such an effect is not apparent in fetal life or in early childhood. This article is protected by copyright. All rights reserved.

Ophthalmic artery Doppler and biomarkers of impaired placentation at 36 weeks' gestation in pregnancies with small fetuses

OBJECTIVES

First, to compare ophthalmic artery peak systolic velocity (PSV) ratio and biomarkers of impaired placentation at 36 weeks' gestation in women who delivered a small-for-gestational-age (SGA) or growth-restricted (FGR) neonate, in the absence of hypertensive disorder, with those of women who developed pre-eclampsia (PE) or gestational hypertension (GH) and of women unaffected by SGA, FGR, PE or GH. Second, to examine the associations of PSV ratio, uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) with birth-weight Z-score or percentile.

METHODS

This was a prospective observational study of women with a singleton pregnancy attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination of fetal anatomy and growth, and measurement of maternal ophthalmic artery PSV ratio, UtA-PI, PlGF and sFlt-1. Values of PSV ratio, UtA-PI, PlGF and sFlt-1 were converted to multiples of the median (MoM) or delta values. Median MoM or deltas of these biomarkers in the SGA, FGR, PE and GH groups were compared with those in the unaffected group. Regression analysis was used to examine the relationship of PSV ratio delta, UtA-PI MoM, PlGF MoM and sFlt-1 MoM with birth-weight Z-score, after exclusion of PE and GH cases.

RESULTS

The study population of 9033 pregnancies included 7696 (85.2%) that were not affected by FGR, SGA, PE or GH, 182 (2.0%) complicated by FGR in the absence of PE or GH, 698 (7.7%) with SGA in the absence of FGR, PE or GH, 236 (2.6%) with PE and 221 (2.4%) with GH. Compared with unaffected pregnancies, in the FGR and SGA groups, the PSV ratio delta and sFlt-1 MoM were increased and PlGF MoM was decreased; UtA-PI MoM was increased in the FGR group but not the SGA group. The magnitude of the changes in biomarker values relative to the unaffected group was smaller in the FGR and SGA groups than that in the PE and GH groups. In non-hypertensive pregnancies, there were significant inverse associations of PSV ratio delta and UtA-PI MoM with birth-weight Z-score, such that the values were increased in small babies and decreased in large babies. There was a quadratic relationship between PlGF MoM and birth-weight Z-score, with low PlGF levels in small babies and high PlGF levels in large babies. There was no significant association between sFlt-1 MoM and birth-weight Z-score.

CONCLUSIONS

Ophthalmic artery PSV ratio, reflective of peripheral vascular resistance, and UtA-PI, PlGF and sFlt-1, biomarkers of impaired placentation, are altered in pregnancies complicated by hypertensive disorder and, to a lesser extent, in non-hypertensive pregnancies delivering a SGA or FGR neonate. The associations between the biomarkers and birth-weight Z-score suggest the presence of a continuous physiological relationship between fetal size and peripheral vascular resistance and placentation, rather than a dichotomous relationship of high peripheral resistance and impaired placentation in small compared to non-small fetuses. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Incidence of neonatal morbidity in small-for-gestational-age twins based on singleton and twin charts

OBJECTIVE

To compare morbidity, as measured by length of stay in the neonatal intensive care unit (NICU), in twin and singleton gestations classified as small-for-gestational age (SGA) according to estimated fetal weight < 10th percentile on twin or singleton growth charts.

METHODS

NICU length of stay was compared in 1150 twins and 29 035 singletons that underwent ultrasound assessment between 35 + 0 and 36 + 6 weeks' gestation. Estimated fetal weight was obtained from measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Gestational age was derived from the first-trimester crown-rump length measurement, using the larger of the two twins. Singletons and twins were compared in terms of NICU admission rate and length of stay according to classification as SGA by the Fetal Medicine Foundation singleton and twin reference distributions.

RESULTS

The overall proportions of twins and singletons admitted to NICU were similar (7.3% vs 7.4%), but twins tended to have longer lengths of stay in NICU (≥ 7 days: 2.4% vs 0.8%; relative risk (RR), 3.0 (95% CI, 1.6-4.4)). Using the singleton chart, a higher proportion of twins were classified as SGA compared with singletons (37.6% vs 7.0%). However, the proportion of SGA neonates entering NICU was similar (10.2% for twins and 10.1% for singletons) and the proportion of SGA neonates spending ≥ 7 days in NICU was substantially higher for twins compared with singletons (3.7% vs 1.4%; RR, 2.6 (95% CI, 1.4-4.7)).

CONCLUSIONS

When singleton charts are used to define SGA in twins and in singletons, there is a greater degree of growth-related neonatal morbidity amongst SGA twins compared with SGA singletons. Consequently, singleton charts do not inappropriately overdiagnose fetal growth restriction in twins and they should be used for monitoring fetal growth in both twins and singletons. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Comparison of different methods of screening for preterm pre-eclampsia: cohort study

OBJECTIVE

To compare the predictive performance for pre-eclampsia (PE) of three different first-trimester mathematical models of screening, which combine maternal risk factors with mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF), and two risk scoring systems, based on NICE and ACOG recommendations.

METHODS

This was a prospective cohort study performed in eight fetal-medicine units in five different regions of Spain between September 2017 and December 2019. All pregnant women with singleton pregnancies and non-malformed live fetuses attending their routine ultrasound examination at 11+0 to 13+6 weeks' gestation were invited to participate in the study. Maternal characteristics and medical history were recorded and measurements of MAP, UtA-PI, serum PlGF and pregnancy associated plasma protein-A (PAPP-A) were converted into multiples of the median (MoM). Risks for term, preterm-PE (< 37 weeks' gestation) and early-PE (< 34 weeks' gestation) were calculated according to the FMF competing risks model, the Crovetto et al., logistic regression model, and Serra et al., Gaussian model. Patient classification based on NICE and ACOG guidelines was also performed. We estimated detection rates (DR) with their 95% confidence intervals (CIs) at a fixed 10% screen positive rate (SPR), as well as the area under the receiver operating characteristic curve (AUROC) for preterm-PE, early-PE, and all PE for the three mathematical models. For the scoring systems, we calculated DR and SPR. Risk calibration was also assessed.

RESULTS

The study population comprised of 10,110 singleton pregnancies, including 32 (0.3%) that developed early-PE, 72 (0.7%) that developed preterm-PE and 230 (2.3%) of any PE. At fixed 10% SPR, the FMF, Crovetto et al., and Serra et al., detected 82.7% (95% CI, 69.6 to 95.8%), 73.8% (95% CI, 58.7 to 88.9%), and 79.8% (95% CI, 66.1 to 93.5%) of early-PE; 72.7% (95% CI, 62.9 to 82.6%), 69.2% (95% CI, 58.8 to 79.6%), and 74.1% (95% CI, 64.2 to 83.9%) of preterm-PE and 55.1% (95% CI, 48.8 to 61.4%), 47.1% (95% CI, 40.6 to 53.5%), and 53.9% (95% CI, 47.4 to 60.4%) of all PE, respectively. The best correlation between predicted and observed cases was achieved by the FMF model, with an AUROC of 0.911 (95% CI, 0.879 to 0.943), a slope of 0.983 (95% CI, 0.846-1.120) and an intercept of 0.154 (95% CI, -0.091 to 0.397). The NICE criteria identified 46.7% (95% CI, 35.3 to 58.0%) of preterm-PE at 11% SPR and ACOG criteria identified 65.9% (95% CI, 55.4 to 76.4%) of preterm-PE at 33.8% SPR.

CONCLUSIONS

The best performance of screening for preterm-PE is achieved by mathematical models that combine maternal factors with MAP, UtA-PI and PlGF, as compared to risk-scoring systems like NICE or ACOG criteria. While all three algorithms show similar results in terms of overall prediction, the FMF model showed the best performance at the individual level. This article is protected by copyright. All rights reserved.

Maternal cardiovascular function at mid-gestation is related to placental angiogenesis

OBJECTIVE

To investigate whether placental function, reflected in the levels of angiogenic factors, is associated with maternal cardiac function and hemodynamic responses at 19 to 24 weeks' gestation after adjustment for maternal risk factors and pregnancy complications.

METHODS

Prospective study on women with singleton pregnancies attending Kings' College Hospital, London, UK for a routine hospital visit at 19-24 weeks' gestation. We recorded maternal characteristics and measured mean arterial pressure, maternal heart rate, serum placental growth factor and soluble fms-like tyrosine kinase 1 (sFLT-1). We also performed maternal echocardiogram to assess cardiac output and peripheral vascular resistance as well as indices of diastolic and systolic function.

RESULTS

Our cohort included 4006 women. Lower placental growth factor (PlGF) values were significantly associated with higher mean arterial pressure (MAP) (p<0.001), lower maternal heart rate (p<0.001), lower mitral valve s' velocity (p= 0.027) and higher left atrial volume (p=0.022) after adjustment for maternal characteristics and pregnancy complications. sFLT-1 was positively related to relative wall thickness (p= 0.012), whereas sFLT-1/ PlGF ratio was negatively associated with mitral valve A (p= 0.006) and positively associated with left atrial volume (p= 0.015) and MAP (p= 0.004). The magnitude of these associations was similar in the subgroup of women without any risk factors from their obstetric and medical history.

CONCLUSION

A continuous link of moderate strength between angiogenic factors and subclinical maternal cardiac function alterations is present at mid-gestation, independently of preexisting maternal risk factors and pregnancy complications. Impaired placental function appears to be related to a mild systolic and diastolic dysfunction and cardiac remodeling. This article is protected by copyright. All rights reserved.

Ophthalmic artery Doppler at 36 weeks' gestation in prediction of pre-eclampsia: validation and update of previous model

OBJECTIVE

To validate and extend a model incorporating maternal ophthalmic artery Doppler at 35-37 weeks' gestation in the prediction of subsequent development of pre-eclampsia (PE).

METHODS

This was a prospective validation study of screening for PE (defined according to the 2019 American College of Obstetricians and Gynecologists criteria) by maternal ophthalmic artery peak systolic velocity (PSV) ratio in 6746 singleton pregnancies undergoing routine care at 35 + 0 to 36 + 6 weeks' gestation (validation dataset). Additionally, the data from the validation dataset were combined with those of 2287 pregnancies that were previously used for development of the model (training dataset), and the combined data were used to update the original model parameters. The competing-risks model was used to estimate the individual patient-specific risk of delivery with PE at any time and within 3 weeks from assessment by a combination of maternal demographic characteristics and medical history with PSV ratio alone and in combination with the established PE biomarkers of mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum soluble fms-like tyrosine kinase-1 (sFlt-1). We evaluated the predictive performance of the model by examining, first, the ability to discriminate between the PE and non-PE groups using the area under the receiver-operating-characteristics curve and the detection rate (DR) at fixed screen-positive (SPR) and false-positive rates of 10% and, second, calibration by measuring the calibration slope and calibration-in-the-large. McNemar's test was used to compare the performance of screening by a biophysical test (maternal factors, MAP, UtA-PI and PSV ratio) vs a biochemical test (maternal factors, PlGF and sFlt-1), low PlGF concentration (< 10th percentile) or high sFlt-1/PlGF concentration ratio (> 90th percentile).

RESULTS

In the validation dataset, the performance of screening by maternal factors and PSV ratio for delivery with PE within 3 weeks and at any time after assessment was consistent with that in the training dataset, and there was good agreement between the predicted and observed incidence of PE. In the combined data from the training and validation datasets, good prediction for PE was achieved in screening by a combination of maternal factors, MAP, UtA-PI, PlGF, sFlt-1 and PSV ratio, with a DR, at a 10% SPR, of 85.0% (95% CI, 76.5-91.4%) for delivery with PE within 3 weeks and 65.7% (95% CI, 59.2-71.7%) for delivery with PE at any time after assessment. The performance of a biophysical test was superior to that of screening by low PlGF concentration or high sFlt-1/PlGF concentration ratio but not significantly different from the performance of a biochemical test combining maternal factors with PlGF and sFlt-1 for both PE within 3 weeks and PE at any time after assessment.

CONCLUSION

Maternal ophthalmic artery PSV ratio at 35-37 weeks' gestation in combination with other biomarkers provides effective prediction of subsequent development of PE. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Fetal Medicine Foundation charts for fetal growth in twins

OBJECTIVE

To derive reference distributions of estimated fetal weight (EFW) in twins relative to singletons.

METHODS

Gestational-age- and chorionicity-specific reference distributions for singleton percentiles and EFW were fitted to data on 4391 twin pregnancies with two liveborn fetuses from four European centers, including 3323 dichorionic (DC) and 1068 monochorionic diamniotic (MCDA) twin pregnancies. Gestational age was derived using the larger of the two crown-rump length measurements obtained during the first trimester of pregnancy. EFW was obtained from ultrasound measurements of head circumference, abdominal circumference and femur length using the Hadlock formula. Singleton percentiles were obtained using the Fetal Medicine Foundation population weight charts for singleton pregnancies. Hierarchical models were fitted to singleton Z-scores with autoregressive terms for serial correlations within the same fetus and between twins from the same pregnancy. Separate models were fitted for DC and MCDA twins.

RESULTS

Fetuses from twin pregnancies tended to be smaller than singletons at the earliest gestational ages (16 weeks for MCDA and 20 weeks for DC twins). This was followed by a period of catch-up growth until around 24 weeks. After that, both DC and MCDA twins showed reduced growth. In DC twins, the EFW corresponding to the 50th percentile was at the 50th percentile of singleton pregnancies at 23 weeks, the 43rd percentile at 28 weeks, the 32nd percentile at 32 weeks and the 22nd percentile at 36 weeks. In MCDA twins, the EFW corresponding to the 50th percentile was at the 36th percentile of singleton pregnancies at 24 weeks, the 29th percentile at 28 weeks, the 19th percentile at 32 weeks and the 12th percentile at 36 weeks.

CONCLUSIONS

In DC and, to a greater extent, MCDA twin pregnancies, fetal growth is reduced compared with that observed in singleton pregnancies. Furthermore, after 24 weeks, the divergence in growth trajectories between twin and singleton pregnancies becomes more pronounced as gestational age increases. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for pre-eclampsia by maternal serum glycosylated fibronectin and angiogenic markers at 36 weeks' gestation

OBJECTIVES

First, to examine the predictive performance of maternal serum glycosylated fibronectin (GlyFn) at 35 + 0 to 36 + 6 weeks' gestation in screening for delivery with pre-eclampsia (PE) and delivery with gestational hypertension (GH) at ≥ 37 weeks' gestation, both within 3 weeks and at any time after the examination. Second, to compare the predictive performance for delivery with PE and delivery with GH of various combinations of biomarkers, including GlyFn, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1). Third, to compare the predictive performance for delivery with PE and delivery with GH by serum PlGF concentration, sFlt-1/PlGF concentration ratio and the competing-risks model with different combinations of biomarkers as above. Fourth, to compare the predictive performance of screening at 11 + 0 to 13 + 6 weeks vs 35 + 0 to 36 + 6 weeks for delivery with PE and delivery with GH at ≥ 37 weeks' gestation.

METHODS

This was a case-control study in which maternal serum GlyFn was measured in stored samples from a non-intervention screening study in singleton pregnancies at 35 + 0 to 36 + 6 weeks' gestation using a point-of-care device. We used samples from women who delivered at ≥ 37 weeks' gestation, including 100 who developed PE, 100 who developed GH and 600 controls who did not develop PE or GH. In all cases, MAP, UtA-PI, PlGF and sFlt-1 were measured during the routine visit at 35 + 0 to 36 + 6 weeks. We used samples from patients that had been examined previously at 11 + 0 to 13 + 6 weeks' gestation. Levels of GlyFn were transformed to multiples of the expected median (MoM) values after adjusting for maternal demographic characteristics and elements from the medical history. Similarly, the measured values of MAP, UtA-PI, PlGF and sFlt-1 were converted to MoM. The competing-risks model was used to combine the prior distribution of the gestational age at delivery with PE, obtained from maternal risk factors, with various combinations of biomarker MoM values to derive the patient-specific risks of delivery with PE. The performance of screening of different strategies was estimated by examining the detection rate (DR) at a 10% fixed false-positive rate (FPR) and McNemar's test was used to compare the DRs between the different methods of screening.

RESULTS

The DR, at 10% FPR, of screening by the triple test (maternal risk factors plus MAP, PlGF and sFlt-1) was 83.7% (95% CI, 70.3-92.7%) for delivery with PE within 3 weeks of screening and 80.0% (95% CI, 70.8-87.3%) for delivery with PE at any time after screening, and this performance was not improved by the addition of GlyFn. The performance of screening by a combination of maternal risk factors, MAP, PlGF and GlyFn was similar to that of the triple test, both for delivery with PE within 3 weeks and at any time after screening. The performance of screening by a combination of maternal risk factors, MAP, UtA-PI and GlyFn was similar to that of the triple test, and they were both superior to screening by low PlGF concentration (PE within 3 weeks: DR, 65.3% (95% CI, 50.4-78.3%); PE at any time: DR, 56.0% (95% CI, 45.7-65.9%)) or high sFlt-1/PlGF concentration ratio (PE within 3 weeks: DR, 73.5% (95% CI, 58.9-85.1%); PE at any time: DR, 63.0% (95% CI, 52.8-72.4%)). The predictive performance of screening at 35 + 0 to 36 + 6 weeks' gestation for delivery with PE and delivery with GH at ≥ 37 weeks' gestation was by far superior to screening at 11 + 0 to 13 + 6 weeks.

CONCLUSION

GlyFn is a potentially useful biomarker in third-trimester screening for term PE and term GH, but the findings of this case-control study need to be validated by prospective screening studies. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler in women with hypertensive disorders of pregnancy: relationship to blood pressure control and renal dysfunction at 6-9 weeks postnatally

OBJECTIVE

To examine the postnatal course of the ophthalmic artery (OA) Doppler in women with hypertensive disorders of pregnancy (HDP) and evaluate the correlation between OA Dopplers and poor postnatal blood pressure control and renal dysfunction at 2-3 and 6-9 weeks postnatally.

METHODS

Prospective cohort study of women with singleton pregnancies with HDP in a tertiary Pregnancy Hypertension clinic. Three visits were included: 1) the last antenatal hypertension clinic visit within 2 weeks prior to delivery, 2) 2-3 weeks postnatally, 3) 6-9 weeks postnatally. At each visit, maternal demographics, medical history, blood pressure and maternal OA Dopplers were performed. In addition, antenatally, fetal growth and fetal Dopplers were examined and at 6-9 weeks postnatally, estimated glomerular filtration rate and proteinuria were quantified. Study participants were divided into four hypertension groups, according to the blood pressure changes with time during the three visits. For the postnatal visits, hypertension was defined as systolic blood pressure (SBP) ≥140 mmHg and / or diastolic(D) BP ≥ 90 mmHg or SBP ≥130 mmHg or DBP ≥ 80 mmHg whilst taking antihypertensives. Group 1 was hypertensive in all three visits, Group 2 was hypertensive in the first two visits but was normotensive in the third visit, Group 3 was hypertensive in visits one and three, but normotensive in visit two, and Group 4 was hypertensive in visit one but normotensive in visits two and three. The longitudinal changes of mean arterial pressure (MAP) and peak systolic velocity (PSV) 1, PSV2 and the ratio of PSV2 / PSV1 over the three time points were examined by a repeated measure, multilevel linear mixed-effects analysis, controlling for maternal age, booking weight and use of antihypertensives. In addition, we examined the longitudinal change of OA Dopplers in women with different degrees of postnatal blood pressure control and in those with and without renal dysfunction at 6-9 weeks' postnatally.

RESULTS

108 women (86 new-onset and 22 chronic hypertension) were recruited into the study. When controlling for maternal age, booking weight and use of antihypertensive medication, a significant decline in Log10 MAP (p<0.001), Log10 PSV1 (p<0.01) and Log10 PSV 2 (p=0.01) was seen between visits 1 and 3. The Log10 PSVR did not change with time (p=0.06). When assessing OA Dopplers against hypertension group, Log10 PSV1 and Log10 PSV2 did not differ between the hypertension groups whilst group 4 had a lower Log10 PSVR compared to groups 1 (p<0.01), 2 (p=0.03) and 3 (p<0.01). When assessing renal dysfunction at 6-9 weeks postnatally, Log10 PSVR was lower in those without than with renal dysfunction (-0.021, p=0.01), whilst Log10 MAP, Log10 PSV1 and Log10 PSV2 values did not differ. The Log10 PSVR did not change with time and remained -0.12 (95%CI, -0.13 to -0.11) across the three visits.

CONCLUSIONS

In women with HDP, the OA-PSVR was significantly higher in those with labile or persistently raised blood pressure postnatally when compared to women whose blood pressure normalised. Similarly, the OA-PSVR at 6-9 weeks postnatally was significantly higher in women with renal dysfunction versus those without dysfunction. This article is protected by copyright. All rights reserved.

Prediction using serum glycosylated fibronectin and angiogenic factors of superimposed pre-eclampsia in women with chronic hypertension

OBJECTIVE

To compare the predictive performance for delivery with pre-eclampsia (PE) within 2 weeks of assessment in women with chronic hypertension at 24-41 weeks' gestation between serum glycosylated fibronectin (GlyFn) concentration, serum placental growth factor (PlGF) concentration and soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio.

METHODS

This was a prospective study of 104 women with a singleton pregnancy and chronic hypertension presenting at 24-41 weeks' gestation. Twenty-six (25.0%) cases developed superimposed PE within 2 weeks of sampling. We compared the predictive performance for superimposed PE between GlyFn, PlGF and the sFlt-1/PlGF ratio at a fixed screen-positive rate of approximately 10%.

RESULTS

The median gestational age at sampling was 34.1 (interquartile range, 31.5-35.6) weeks and 84.6% (88/104) of cases were sampled at < 36 weeks. The predictive performance for superimposed PE of the three methods of screening was similar, with detection rates of about 23-27%, at a screen-positive rate of 11% and a false-positive rate of about 5%.

CONCLUSIONS

Measurement of GlyFn is a simple point-of-care test that can be carried out without need for a laboratory and provide results within 10 min of testing. In this respect, it could potentially replace the angiogenic markers that are used currently in the prediction of imminent PE in high-risk women. However, neither GlyFn nor angiogenic factors are likely to improve the management of women with chronic hypertension because their predictive performance for superimposed PE is poor. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Three-dimensional echocardiography and strain cardiac imaging in women with pre-eclampsia with follow-up to 6 months postpartum

OBJECTIVE

Epidemiological studies have established that women with pre-eclampsia (PE) are at increased long-term cardiovascular risk. Mild cardiac functional changes have been documented during pregnancy in women with PE, but their evolution from presentation to the postpartum period remains poorly defined. The aim of this study was to assess biventricular cardiovascular indices using novel and sensitive two-dimensional and three-dimensional (3D) echocardiographic modalities in pregnancy and to track alterations in both risk factors and cardiovascular indices in the postpartum period.

METHODS

A total of 59 women with PE were examined at 34 (interquartile range, 31-37) weeks' gestation and at 2-3 days, 3 months and 6 months postpartum. During pregnancy, 118 women with a normotensive pregnancy were also recruited as controls. Biventricular ejection fraction and left ventricular mass were measured by 3D echocardiography. Biventricular global longitudinal strain and strain of the left atrium were assessed using speckle-tracking imaging.

RESULTS

In women with PE, compared with controls, there was lower left ventricular diastolic function (left atrial reservoir strain, 44.1% vs 49.2%) and increased left ventricular mass index (148 vs 128 g/m2 ), but there was no significant difference in right ventricular functional indices. These alterations in cardiac indices were mostly explained by differences in maternal risk factors. In the postpartum period, most cardiac indices improved by 3 months. Multivariable linear mixed-model analysis demonstrated that this improvement was mostly attributed to reduction in weight and blood pressure.

CONCLUSION

In women with PE, there is postpartum improvement in cardiac functional and structural indices in parallel with improvement in their risk factor profile. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction using serum glycosylated fibronectin of imminent pre-eclampsia in women with new-onset hypertension

OBJECTIVE

To compare the predictive performance for delivery with pre-eclampsia (PE) within 2 weeks after assessment in women with new-onset hypertension at 24-41 weeks' gestation between serum glycosylated fibronectin (GlyFn) concentration, serum placental growth factor (PlGF) concentration and soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio.

METHODS

This was a prospective observational study of 409 women with a singleton pregnancy presenting at 24-41 weeks' gestation with new-onset hypertension. The recommended cut-off for sFlt-1/PlGF ratio for the prediction of PE in the platform used in this study is 85; the appropriate cut-offs for GlyFn and PlGF were determined to achieve the same screen-positive rate as that of sFlt-1/PlGF ratio > 85. We then compared the predictive performance for delivery with PE within 2 weeks after presentation between GlyFn, PlGF and sFlt-1/PlGF, both overall and in subgroups according to gestational age at presentation.

RESULTS

Delivery with PE within 2 weeks occurred in 93 (22.7%) cases. The screen-positive rate for sFlt-1/PlGF ratio > 85 was 46.2%. The cut-off corresponding to a screen-positive rate of 46.2% was 75 pg/mL for PlGF and 510 µg/mL for GlyFn. The overall detection rate for delivery with PE within 2 weeks after presentation was 62.4% (95% CI, 51.7-72.2%) for GlyFn and sFlt-1/PlGF and 60.2% (95% CI, 49.5-70.2%) for PlGF. In all women who delivered with PE within 2 weeks after presentation at < 34 weeks' gestation and in about 60-70% of those presenting at < 38 weeks, GlyFn and sFlt-1/PlGF were increased and PlGF was reduced. However, the screen-positive rate for these tests was very high at about 45%. The predictive performance for delivery with PE within 2 weeks after presentation at ≥ 38 weeks' gestation was poorer for all three methods of screening, with detection rates of 47-63% at screen-positive rates of 40-50%.

CONCLUSIONS

In women with new-onset hypertension, the predictive performance for delivery with PE within 2 weeks after presentation for serum GlyFn is similar to that of PlGF and the sFlt-1/PlGF ratio, but GlyFn may be the preferred option because it is a rapid point-of-care test. However, the predictive performance for all tests is relatively poor. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Screening for pre-eclampsia by maternal serum glycosylated fibronectin at 11-13 weeks' gestation

OBJECTIVE

To examine the performance of screening for preterm and term pre-eclampsia (PE) at 11-13 weeks' gestation by maternal factors and combinations of maternal serum glycosylated fibronectin (GlyFn), mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF).

METHODS

This was a case-control study in which maternal serum GlyFn was measured using a point-of-care device in stored samples from a non-intervention screening study of singleton pregnancies at 11 + 0 to 13 + 6 weeks' gestation. In the same samples, PlGF was measured by time-resolved fluorometry. We used samples from women who delivered with PE at < 37 weeks' gestation (n = 100), PE at ≥ 37 weeks (n = 100), gestational hypertension (GH) at < 37 weeks (n = 100), GH at ≥ 37 weeks (n = 100) and 1000 normotensive controls with no pregnancy complications. In all cases, MAP and UtA-PI had been measured during the routine 11-13-week visit. Levels of GlyFn were transformed to multiples of the expected median (MoM) values after adjusting for maternal demographic characteristics and elements of medical history. Similarly, the measured values of MAP, UtA-PI and PlGF were converted to MoMs. The competing-risks model was used to combine the prior distribution of gestational age at delivery with PE, obtained from maternal characteristics, with various combinations of biomarker MoM values to derive the patient-specific risks of delivery with PE or GH at < 37 and ≥ 37 weeks' gestation. Screening performance was estimated by examining the area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at 10% fixed false-positive rate (FPR).

RESULTS

The maternal characteristics and elements of medical history with a significant effect on the measurement of GlyFn were maternal age, weight, height, race, smoking status and history of PE. In pregnancies that developed PE, GlyFn MoM was increased and the deviation from normal decreased with increasing gestational age at delivery. The DR and AUC of screening for delivery with PE at < 37 weeks' gestation by maternal factors alone were 50% and 0.834, respectively, and these increased to 80% and 0.949, respectively, when maternal risk factors were combined with MAP, UtA-PI and PlGF (triple test). The performance of the triple test was similar to that of screening by a combination of maternal factors, MAP, UtA-PI and GlyFn (DR, 79%; AUC, 0.946) and that of screening by a combination of maternal factors, MAP, PlGF and GlyFn (DR, 81%; AUC, 0.932). The performance of screening for delivery with PE at ≥ 37 weeks' gestation was poor; the DR for screening by maternal factors alone was 35% and increased to only 39% with use of the triple test. Similar results were obtained when GlyFn replaced PlGF or UtA-PI in the triple test. The DR of screening for GH with delivery at < 37 and ≥ 37 weeks' gestation by maternal factors alone was 34% and 25%, respectively, and increased to 54% and 31%, respectively, with use of the triple test. Similar results were obtained when GlyFn replaced PlGF or UtA-PI in the triple test.

CONCLUSIONS

GlyFn is a potentially useful biomarker in first-trimester screening for preterm PE, but the findings of this case-control study need to be validated by prospective screening studies. The performance of screening for term PE or GH at 11 + 0 to 13 + 6 weeks' gestation by any combination of biomarkers is poor. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of hypertensive disorders after screening at 36 weeks' gestation: comparison of angiogenic markers with competing-risks model

OBJECTIVE

To compare the performance at 35 + 0 to 36 + 6 weeks' gestation of screening for delivery with pre-eclampsia (PE) at various timepoints, using one of three approaches: placental growth factor (PlGF) concentration, soluble fms-like tyrosine kinase-1 (sFlt-1) to PlGF concentration ratio, or the competing-risks model, which combines maternal risk factors with biomarkers to estimate patient-specific risk.

METHODS

This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation at one of two maternity hospitals in England between 2016 and 2022. During the visit, maternal demographic characteristics and medical history were recorded and serum PlGF, serum sFlt-1 and mean arterial pressure (MAP) were measured. Detection rates (DRs) were evaluated for delivery with PE (defined as per American College of Obstetricians and Gynecologists 2019 criteria) within 1 week, within 2 weeks or at any time after screening, using the following strategies: (i) low PlGF (< 10th percentile); (ii) high sFlt-1/PlGF ratio (> 90th percentile); or (iii) the competing-risks model, in which maternal factors were combined with multiples of the median values of PlGF ('single test'), PlGF and sFlt-1 ('double test') or PlGF, sFlt-1 and MAP ('triple test'). Risk cut-offs corresponded to a screen-positive rate of 10%. DRs were compared between tests.

RESULTS

Of 34 782 pregnancies, 831 (2.4%) developed PE. In screening for delivery with PE at any time from assessment, the DR at 10% screen-positive rate was 47% by low PlGF alone, 54% by the single test, 55% by high sFlt-1/PlGF ratio, 61% by the double test and 68% by the triple test. In screening for delivery with PE within 2 weeks from assessment, the respective values were 67%, 74%, 74%, 80% and 87%. In screening for delivery with PE within 1 week from assessment, the respective values were 77%, 81%, 85%, 88% and 91%. For prediction of PE at any time, the DR was significantly higher with the triple test compared to PlGF alone or the sFlt-1/PlGF ratio, with a DR difference (95% CI) of 20.1% (16.7-23.0%) and 12.4% (9.7-15.3%), respectively. Similar results were seen for prediction of PE within 2 weeks (20.6% (14.9-26.8%) and 12.9% (7.7-17.5%), respectively) and prediction of PE within 1 week (13.5% (5.4-21.6%) and 5.4% (0.0-10.8%), respectively). The double test was superior to the sFlt-1/PlGF ratio and the single test was superior to PlGF alone in the prediction of PE within 2 weeks and at any time from assessment, but not within 1 week of assessment.

CONCLUSION

At 35 + 0 to 36 + 6 weeks' gestation, the performance of screening for PE by the competing-risks model triple test is superior to that of PlGF alone or the sFlt-1/PlGF ratio for the development of disease within 1 week, within 2 weeks and at any time from screening. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Prediction of adverse perinatal outcome at midgestation

OBJECTIVES

First, to investigate the association between adverse neonatal outcomes and birth weight and gestational age at delivery. Second, to describe the distribution of adverse neonatal outcomes within different risk strata derived by a population stratification scheme based on the midgestation risk assessment for small-for-gestational-age (SGA) neonates using a competing-risks model.

METHODS

This was a prospective observational cohort study in women with a singleton pregnancy attending a routine hospital visit at 19 + 0 to 23 + 6 weeks' gestation. The incidence of neonatal unit (NNU) admission for ≥ 48 h was evaluated within different birth-weight-percentile subgroups. The pregnancy-specific risk of delivery with SGA < 10th percentile at < 37 weeks was estimated by the competing-risks model for SGA, combining maternal factors and the likelihood functions of Z-score of sonographically estimated fetal weight and uterine artery pulsatility index multiples of the median. The population was stratified into six risk categories: > 1 in 4, > 1 in 10 to ≤ 1 in 4, > 1 in 30 to ≤ 1 in 10, > 1 in 50 to ≤ 1 in 30, > 1 in 100 to ≤ 1 in 50 and ≤ 1 in 100. The outcome measures were admission to the NNU for a minimum of 48 h, perinatal death and major neonatal morbidity. The incidence of each adverse outcome was estimated in each risk stratum.

RESULTS

In the study population of 40 241 women, 0.8%, 2.5%, 10.8%, 10.2%, 19.0% and 56.7% were in the risk strata > 1 in 4, > 1 in 10 to ≤ 1 in 4, > 1 in 30 to ≤ 1 in 10, > 1 in 50 to ≤ 1 in 30, > 1 in 100 to ≤ 1 in 50 and ≤ 1 in 100, respectively. Women in higher-risk strata were more likely to deliver a baby that suffered an adverse outcome. The incidence of NNU admission for ≥ 48 h was highest in the > 1 in 4 risk stratum (31.9% (95% CI, 26.9-36.9%)) and it gradually decreased until the ≤ 1 in 100 risk stratum (5.6% (95% CI, 5.3-5.9%)). The mean gestational age at delivery in SGA cases with NNU admission for ≥ 48 h was 32.9 (95% CI, 32.2-33.7) weeks for risk stratum > 1 in 4 and progressively increased to 37.5 (95% CI, 36.8-38.2) weeks for risk stratum ≤ 1 in 100. The incidence of NNU admission for ≥ 48 h was highest for neonates with birth weight below the 1st percentile (25.7% (95% CI, 23.0-28.5%)) and decreased progressively until the 25th to < 75th percentile interval (5.4% (95% CI, 5.1-5.7%)). Preterm SGA neonates < 10th percentile had significantly higher incidence of NNU admission for ≥ 48 h compared with preterm non-SGA neonates (48.7% (95% CI, 45.0-52.4%) vs 40.9% (95% CI, 38.5-43.3%); P < 0.001). Similarly, term SGA neonates < 10th percentile had significantly higher incidence of NNU admission for ≥ 48 h compared with term non-SGA neonates (5.8% (95% CI, 5.1-6.5%) vs 4.2% (95% CI, 4.0-4.4%); P < 0.001).

CONCLUSIONS

Birth weight has a continuous association with the incidence of adverse neonatal outcomes, which is affected by gestational age. Pregnancies at high risk of SGA, estimated at midgestation, are also at increased risk for adverse neonatal outcomes. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

ASPRE trial: effects of aspirin on mean arterial blood pressure and uterine artery pulsatility index trajectories in pregnancy

OBJECTIVES

The mechanism by which aspirin prevents pre-eclampsia is poorly understood, and its effects on biomarkers throughout pregnancy are unknown. We aimed to investigate the effects of aspirin on mean arterial pressure (MAP) and mean uterine artery pulsatility index (UtA-PI) using repeated measures from women at increased risk of preterm pre-eclampsia.

METHODS

This was a longitudinal secondary analysis of the Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Pre-eclampsia Prevention (ASPRE) trial using repeated measures of MAP and UtA-PI. In the trial, 1620 women at increased risk of preterm pre-eclampsia were identified using the Fetal Medicine Foundation algorithm at 11 + 0 to 13 + 6 weeks, of whom 798 were randomly assigned to receive 150 mg/day aspirin and 822 were assigned to receive placebo daily from 11-14 weeks to 36 weeks of gestation or delivery, whichever came first. MAP and UtA-PI were measured at baseline and follow-up visits at 19-24, 32-34 and 36 weeks of gestation. Generalized additive mixed models with treatment by gestational age interaction terms were used to investigate the effects of aspirin on MAP and UtA-PI trajectories over time.

RESULTS

Among 798 participants in the aspirin group and 822 in the placebo group, there were 5951 MAP and 5942 UtA-PI measurements. Trajectories of raw and multiples of the median (MoM) values of MAP did not differ significantly between the two groups (MAP MoM analysis: P-value for treatment by gestational age interaction, 0.340). In contrast, trajectories of raw and MoM values of UtA-PI showed a significantly steeper decline in the aspirin group than in the placebo group, with the difference mainly driven by a more pronounced reduction before 20 weeks of gestation (UtA-PI MoM analysis: P-value for treatment by gestational age interaction, 0.006).

CONCLUSIONS

In women at increased risk of preterm pre-eclampsia, 150 mg/day aspirin initiated in the first trimester does not affect MAP but is associated with a significant decrease in mean UtA-PI, particularly before 20 weeks of gestation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal cardiac function at midgestation and conception by in-vitro fertilization

OBJECTIVE

To assess differences in cardiac morphology and function at midgestation in fetuses conceived by in-vitro fertilization (IVF), using fresh or frozen embryo transfer, compared with those conceived naturally.

METHODS

This was a prospective study of 5801 women with a singleton pregnancy attending for a routine ultrasound examination at 19 + 0 to 23 + 6 weeks' gestation, including 343 that conceived by IVF. Conventional and more advanced echocardiographic modalities, including speckle-tracking analysis, were used to assess fetal cardiac function in the right and left ventricles. The morphology of the fetal heart was assessed by calculating the right and left sphericity index. Placental perfusion and function were assessed by measurement of uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF), respectively.

RESULTS

Fetuses that were conceived by IVF, compared with those conceived spontaneously, had significantly lower right and left ventricular sphericity index, higher left ventricular global longitudinal strain and lower left ventricular ejection fraction. There were no significant differences in any of the cardiac indices within the IVF group between the fresh and frozen embryo transfers. In the IVF group, compared with spontaneously conceived pregnancies, UtA-PI was lower and PlGF was higher, suggesting better placental perfusion and function.

CONCLUSIONS

Our study demonstrates that, in IVF pregnancies, compared with those conceived spontaneously, there is evidence of fetal cardiac remodeling at midgestation, which is not related to the use of fresh or frozen embryo transfer. In the IVF group, compared with naturally conceived pregnancies, fetal heart was globular and left ventricular systolic function was mildly reduced. Whether these cardiac changes are accentuated later in pregnancy and remain in the postnatal period remains to be established. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Vascular phenotype at 35-37 weeks' gestation in women with gestational diabetes mellitus

OBJECTIVES

To examine the vascular phenotype at 35-37 weeks' gestation of women with gestational diabetes mellitus (GDM) and compare it to that in women without GDM, using ophthalmic artery Doppler and carotid-femoral pulse-wave velocity.

METHODS

This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 37 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ophthalmic artery Doppler for calculation of the peak systolic velocity (PSV) ratio and assessment of cardiac output, stroke volume, total peripheral resistance, central systolic and diastolic blood pressure, carotid-femoral pulse-wave velocity and augmentation index. All measurements were standardized to remove the effects of maternal characteristics and elements from the medical history, and the adjusted values in the GDM group were compared with those in the non-GDM group.

RESULTS

The study population of 2018 pregnancies contained 218 (10.8%) that developed GDM, including 78 (35.8%) that were treated with diet alone, 81 (37.2%) treated with metformin and 59 (27.1%) treated with insulin with or without metformin. In the GDM group, compared with the non-GDM group, there were significantly higher ophthalmic artery PSV ratio, carotid-femoral pulse-wave velocity and central systolic blood pressure, but there was no significant difference in cardiac output, stroke volume, total peripheral resistance, central diastolic blood pressure or augmentation index. In the GDM group, women treated with metformin or insulin had a higher ophthalmic artery PSV ratio compared with those treated with diet alone. Additionally, compared with the diet group, the metformin group had higher central systolic blood pressure and the insulin group had a higher carotid-femoral pulse-wave velocity.

CONCLUSION

Women with GDM have evidence of early vascular disease, and this may contribute to their long-term cardiovascular risk. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Atypicality index: avoiding false reassurance in prenatal screening

OBJECTIVE

To demonstrate the application of the atypicality index as an adjunct to first-trimester risk assessment for major trisomies by the combined test.

METHODS

This was a study of 123 998 Danish women with a singleton pregnancy who underwent routine first-trimester screening, including risk assessment for major trisomies. An atypicality index, which is a measure of the degree to which a profile is atypical, was produced for measurements of fetal nuchal translucency thickness and maternal serum free β-human chorionic gonadotropin and pregnancy-associated plasma protein-A. The incidence of adverse pregnancy outcome, including miscarriage, intrauterine death and termination of pregnancy, was tabulated according to the screening result and atypicality index.

RESULTS

In pregnancies with low risk and those with high risk for major trisomies according to the combined screening test, the incidence of adverse pregnancy outcome increased with increasing atypicality index. In pregnancies with a low risk for trisomies and atypicality index of ≥ 99%, the incidence of adverse outcome was 5.1 (95% CI, 3.4-7.6) times higher compared with that in low-risk pregnancies with a typical measurement profile, reflected by an atypicality index of < 80%. Similarly, in high-risk pregnancies, the incidence of adverse outcome was 7.9 (95% CI, 4.4-14.5) times higher in those with an atypicality index of ≥ 99% compared to those with an atypicality index of < 80%. Using individual profile plots, we were able to demonstrate a transparent and intuitive method for visualization of multiple variables, which can help interpret the individual combination of measurements and level of atypicality.

CONCLUSIONS

In pregnancies undergoing first-trimester combined screening and classified as being at low risk for major trisomies, profiles that are typical of pregnancies with normal outcome provide additional reassurance, whereas those with an atypical profile may warrant further investigation. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Incidence of stillbirth: effect of deprivation

OBJECTIVES

To examine the relationship between the English index of multiple deprivation (IMD) and the incidence of stillbirth and assess whether IMD contributes to the prediction of stillbirth provided by the combination of maternal demographic characteristics and elements of medical history.

METHODS

This was a prospective, observational study of 159 125 women with a singleton pregnancy who attended their first routine hospital visit at 11 + 0 to 13 + 6 weeks' gestation in two maternity hospitals in the UK. The inclusion criterion was delivery at ≥ 24 weeks' gestation of a fetus without major abnormality. Participants completed a questionnaire on demographic characteristics and obstetric and medical history. IMD was used as a measure of socioeconomic status, which takes into account income, employment, education, skills and training, health and disability, crime, barriers to housing and services, and living environment. Each neighborhood is ranked according to its level of deprivation relative to that of other areas into one of five equal groups, with Quintile 1 containing the 20% most deprived areas and Quintile 5 containing the 20% least deprived areas. Logistic regression analysis was used to determine whether IMD provided a significant independent contribution to stillbirth after adjustment for known maternal risk factors.

RESULTS

The overall incidence of stillbirth was 0.35% (551/159 125), and this was significantly higher in the most deprived compared with the least deprived group (Quintile 1 vs Quintile 5). The odds ratio (OR) in Quintile 1 was 1.57 (95% CI, 1.16-2.14) for any stillbirth, 1.64 (95% CI, 1.20-2.28) for antenatal stillbirth and 1.89 (95% CI, 1.23-2.98) for placental dysfunction-related stillbirth. In Quintile 1 (vs Quintile 5), there was a higher incidence of factors that contribute to stillbirth, including black race, increased body mass index, smoking, chronic hypertension and previous stillbirth. The OR of black (vs white) race was 2.58 (95% CI, 2.14-3.10) for any stillbirth, 2.62 (95% CI, 2.16-3.17) for antenatal stillbirth and 3.34 (95% CI, 2.59-4.28) for placental dysfunction-related stillbirth. Multivariate analysis showed that IMD did not have a significant contribution to the prediction of stillbirth provided by maternal race and other maternal risk factors. In contrast, in black (vs white) women, the risk of any and antenatal stillbirth was 2.4-fold higher and the risk of placental dysfunction-related stillbirth was 2.9-fold higher after adjustment for other maternal risk factors.

CONCLUSIONS

The incidence of stillbirth, particularly placental dysfunction-related stillbirth, is higher in women living in the most deprived areas in South East England. However, in screening for stillbirth, inclusion of IMD does not improve the prediction provided by race, other maternal characteristics and elements of medical history. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Incidence of pre-eclampsia: effect of deprivation

OBJECTIVES

To examine the relationship between the English index of multiple deprivation (IMD) and the incidence of pre-eclampsia (PE), evaluate the distribution of IMD in a cohort of ethnically diverse pregnant women in South East England and assess whether IMD improves the prediction of PE compared with that provided by the 'history-only' competing-risks model (based on maternal characteristics and medical history).

METHODS

This was a prospective, observational study of 159 125 women with a singleton pregnancy who attended their first routine hospital visit at 11 + 0 to 13 + 6 weeks' gestation in two maternity hospitals in the UK. The inclusion criteria were delivery at ≥ 24 weeks' gestation of babies without major abnormality. Participants completed a questionnaire on demographic characteristics and obstetric and medical history, which was then reviewed by a doctor together with the woman. Patients were asked to self-identify as white, black, South Asian, East Asian or mixed race. IMD was used as a measure of socioeconomic status, which takes into account income, employment, education, skills and training, health and disability, crime, barriers to housing and services, and living environment. Each neighborhood is ranked according to their level of deprivation relative to that of other areas into one of five equal groups, with Quintile 1 containing the 20% most deprived areas and Quintile 5 containing the 20% least deprived areas. IMD was assigned based on a woman's postcode. Risk factors for PE and its incidence were assessed across IMD using chi-square test or t-test, as appropriate. The relationship between IMD and gestational age at delivery with PE was evaluated by fitting parametric survival models for IMD alone, IMD combined with race and IMD combined with the Fetal Medicine Foundation history-only competing-risks model.

RESULTS

The incidence of PE (n = 4088, 2.6%) increased progressively across IMD quintiles, from 2.0% in Quintile 5 (least deprived) to 3.0% in Quintile 1 (most deprived). Compared with white women and those in other racial groups, black women had a higher incidence of PE (4.8%), were less often in IMD Quintiles 4 and 5, and were more often in IMD Quintiles 1 and 2. None of the IMD quintiles improved the prediction of PE compared with that provided by the history-only competing-risks model (which includes race). The history-only competing-risks model with vs without IMD had a similar detection rate for delivery with PE at < 37 weeks' gestation (44.1% (95% CI, 41.1-47.2%) vs 43.9% (95% CI, 40.1-47.0%)) and at any gestational age (35.2% (95% CI, 33.8-36.7%) vs 35.1% (95% CI, 33.7-36.6%)), at a 10% screen-positive rate.

CONCLUSIONS

The incidence of PE is higher in women living in the most deprived areas in South East England and in black women (vs those of other racial groups), who also live in areas of higher deprivation. However, in screening for PE, inclusion of IMD does not improve the prediction of PE provided by race and other maternal characteristics and elements of medical history. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Machine-learning-based prediction of pre-eclampsia using first-trimester maternal characteristics and biomarkers

OBJECTIVE

To evaluate the accuracy of predicting the risk of developing pre-eclampsia (PE) according to first-trimester maternal demographic characteristics, medical history and biomarkers using artificial-intelligence and machine-learning methods.

METHODS

The data were derived from prospective non-interventional screening for PE at 11-13 weeks' gestation at two maternity hospitals in the UK. The data were divided into three subsets. The first set, including 30 437 subjects, was used to develop the training process, the second set of 10 000 subjects was utilized to optimize the machine-learning hyperparameters and the third set of 20 352 subjects was coded and used for model validation. An artificial neural network was used to predict from the demographic characteristics and medical history the prior risk that was then combined with biomarker values to determine the risk of PE and preterm PE with delivery at < 37 weeks' gestation. An additional network was trained without including race as input. Biomarkers included uterine artery pulsatility index (UtA-PI), mean arterial blood pressure (MAP), placental growth factor (PlGF) and pregnancy-associated plasma protein-A. All markers were entered using raw values without conversion into standardized multiples of the median. The prediction accuracy was estimated using the area under the receiver-operating-characteristics curve (AUC). We further computed the detection rate at 10%, 20% and 40% false-positive rates (FPR). The impact of taking aspirin was also added. Shapley values were calculated to evaluate the contribution of each parameter to the prediction of risk. We used a non-parametric test to compare the expected AUC with the one obtained when we randomly scrambled the labels and kept the predictions. For the general prediction, we performed 10 000 permutations of the labels. When the AUC was higher than the one obtained in all 10 000 permutations, we reported a P-value of < 0.0001. For the race-specific analysis, we performed 1000 permutations. When the AUC was higher than the AUC in permutations, we reported a P-value of < 0.001.

RESULTS

The detection rate for preterm PE vs no PE, at a 10% FPR, was 53.3% when screening by maternal factors only, and the corresponding AUC was 0.816; these increased to 75.3% and 0.909, respectively, with the addition of biomarkers into the model. Information on race was important for the prediction accuracy; when race was not used to train the model, at a 10% FPR, the detection rate of preterm PE vs no PE decreased to 34.5-45.5% (for different races) when screening by maternal factors only and to 55.0-62.1% when biomarkers were added. The major predictors of PE were high MAP and UtA-PI, and low PlGF. The accuracy of prediction of all PE cases was lower than that for preterm PE. Aspirin use was recommended for cases who were at high risk of preterm PE. The AUC of all PE vs no PE was 0.770 when screening by maternal factors and 0.817 when the biomarkers were added; the respective detection rates, at a 10% FPR, were 41.3% and 52.9%.

CONCLUSIONS

Screening for PE using a non-linear machine-learning-based approach does not require a population-based normalization, and its performance is similar to that of logistic regression. Removing race information from the model reduces its prediction accuracy, especially for the non-white populations when only maternal factors are considered. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Competing-risks model for prediction of small-for-gestational-age neonate at 36 weeks' gestation

OBJECTIVES

To develop further a competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate by including sonographically estimated fetal weight (EFW) and biomarkers of impaired placentation at 36 weeks' gestation, and to compare the performance of the new model with that of the traditional EFW < 10^th percentile cut-off.

METHODS

This was a prospective observational study in 29 035 women with a singleton pregnancy undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. A competing-risks model for the prediction of a SGA neonate was used. The parameters included in the prior-history model were provided in previous studies. An interaction continuous model was used for the EFW likelihood. A folded plane regression model was fitted to describe likelihoods of biomarkers of impaired placentation. Stratification plans were also developed. The new model was evaluated and compared with EFW percentile cut-offs.

RESULTS

The performance of the model was better for predicting SGA neonates delivered closer to the point of assessment. The prediction provided by maternal factors alone was improved significantly by the addition of EFW, uterine artery pulsatility index (UtA-PI) and placental growth factor (PlGF) but not by mean arterial pressure or soluble fms-like tyrosine kinase-1. At a 10% false-positive rate, maternal factors and EFW predicted 77.6% and 65.8% of SGA neonates < 10^th percentile delivered before 38 and 42 weeks, respectively. The respective figures for SGA < 3^rd percentile were 85.5% and 74.2%. Addition of UtA-PI and PlGF resulted in marginal improvement in prediction of SGA < 3^rd percentile requiring imminent delivery. A competing-risks approach that combines maternal factors and EFW performed better when compared with fixed EFW percentile cut-offs at predicting a SGA neonate, especially with increasing time interval between assessment and delivery. The new model was well-calibrated.

CONCLUSIONS

A competing-risks model provides effective risk stratification for a SGA neonate at 35 + 0 to 36 + 6 weeks' gestation and is superior to EFW percentile cut-offs. The use of biomarkers of impaired placentation in addition to maternal factors and fetal biometry results in small improvement of the predictive performance for a neonate with severe SGA. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Impact of maternal height, weight at presentation and gestational weight gain on cardiac adaptation in pregnancy

OBJECTIVE

To compare longitudinal maternal hemodynamic changes throughout gestation between different groups stratified according to weight at presentation and assess the relative influence of height, weight at presentation and gestational weight gain on cardiac adaptation.

METHODS

This was a prospective, longitudinal study assessing maternal hemodynamics using bioreactance technology at 11 + 0 to 13 + 6, 19 + 0 to 24 + 0, 30 + 0 to 34 + 0 and 35 + 0 to 37 + 0 weeks' gestation. Women were divided into three groups according to maternal weight at presentation at the first visit at 11 + 0 to 13 + 6 weeks: Group 1, &lt; 60.0 kg (n = 421); Group 2, 60.0-79.7 kg (n = 904); Group 3, &gt; 79.7 kg (n = 427). A multilevel linear mixed-effects model was used to compare the repeated measures of hemodynamic variables, correcting for demographics, medical and obstetric history, pregnancy complications, maternal weight and time of evaluation. The linear mixed-effects model was then repeated using maternal height, weight at presentation and gestational weight gain Z-scores, and the standardized coefficients were used to evaluate the relative impact of each of these demographic parameters on longitudinal changes of maternal hemodynamics.

RESULTS

Compared with Group 1, women in Group 3 demonstrated higher cardiac output (CO), heart rate (HR) and mean arterial pressure (MAP) throughout pregnancy. Groups 2 and 3 had higher stroke volume (SV) than Group 1 at the first visit, but their SV plateaued between the first and second visits and demonstrated an earlier significant decrease from the second visit to the third visit when compared with Group 1. Compared with Groups 1 and 2, there was a higher prevalence of pre-eclampsia, gestational hypertension and gestational diabetes in Group 3. Maternal height was the most important contributor to CO, peripheral vascular resistance (PVR), SV and HR, while weight at presentation was the most important contributor to MAP. Gestational weight gain was the second most important characteristic influencing the longitudinal changes of PVR and SV.

CONCLUSIONS

Women with greater weight at presentation have a pathological hemodynamic profile, with higher CO, HR and MAP compared to women with lower weight at presentation. Height is the main determinant of CO, SV, HR and PVR, weight is the main determinant of MAP, and gestational weight gain is the second most important determinant of SV and PVR. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Competing-risks model for pre-eclampsia and adverse pregnancy outcomes

OBJECTIVE

The competing-risks model for assessment of risk for pre-eclampsia (PE) at 35-37 weeks' gestation identifies the majority of women who are at high risk of subsequent delivery with PE. We aimed to examine the incidence and relative risk of adverse pregnancy outcomes in patient groups stratified according to the estimated risk of delivery with PE.

METHODS

This was a prospective non-interventional, observational study in women with a singleton pregnancy attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. The risk of delivery with PE for each patient in the study population was estimated using the competing-risks model, combining the prior distribution of gestational age at delivery with PE and the likelihood from multiples of the median values of mean arterial pressure, placental growth factor and soluble fms-like tyrosine kinase-1. The patients were assigned to one of the following five risk categories: Group A, ≥ 1 in 2; Group B, 1 in 5 to 1 in 3; Group C, 1 in 20 to 1 in 6; Group D, 1 in 50 to 1 in 21; and Group E, < 1 in 50. The outcome measures were delivery with PE, gestational hypertension (GH), small-for-gestational age (SGA) at birth, delivery by Cesarean section, stillbirth, neonatal death, perinatal death and admission to the neonatal unit (NNU) for at least 48 h. In each risk category, the proportion of women with each adverse outcome was determined and relative risks (RR) were calculated as compared with the lowest-risk Group E.

RESULTS

In the study population of 29 035 women, 1.6%, 2.7%, 8.2%, 9.8% and 77.8% were categorized into Groups A, B, C, D and E, respectively. Compared with women in Group E, women in the higher-risk groups were more likely to have an adverse outcome. The RR of delivery with PE in Group A compared with Group E was 65.5 (95% CI, 54.1-79.1) and the respective values were 11.9 (95% CI, 9.1-15.5) for GH, 1.8 (95% CI, 1.5-2.1) for delivery by emergency Cesarean section, 1.5 (95% CI, 1.2-1.8) for delivery by elective Cesarean section, 8.9 (95% CI, 7.4-10.8) for SGA with birth weight < 3^rd percentile, 4.8 (95% CI, 4.3-5.4) for SGA with birth weight < 10^th percentile, 5.3 (95% CI, 1.4-20.5) for stillbirth and 3.4 (95% CI, 2.8-4.2) for NNU admission for ≥ 48 h. The RR for these pregnancy complications in higher-risk groups (vs Group E) was particularly high for cases with delivery within 2 weeks after assessment. In terms of SGA, both for birth weight < 10^th and < 3^rd percentiles, the trend in all cases was stronger than that observed when the analysis was confined to normotensive pregnancies. The rates of neonatal death were too small to allow meaningful comparisons between risk groups.

CONCLUSION

Pregnant women identified by the competing-risks model to be at high risk of PE are also at increased risk of GH, Cesarean section, stillbirth, SGA and NNU admission for ≥ 48 h. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Midgestation cardiovascular phenotype in women who develop gestational diabetes and hypertensive disorders of pregnancy: comparative study

OBJECTIVE

Women with gestational diabetes mellitus (GDM) and/or hypertensive disorders of pregnancy (HDP) are at increased long-term cardiovascular risk. Mild cardiac functional alterations have been detected in women with GDM or HDP in midgestation, prior to clinical onset of the disease, but these functional alterations have not been found to be useful as screening tools. In contrast, increased impedance to peripheral blood flow, measured by echocardiography or ophthalmic artery Doppler, has been shown to provide incremental value to maternal characteristics for the prediction of pre-eclampsia. However, it is unknown whether similar changes can be detected in women at risk of GDM. In this study, we performed detailed cardiovascular phenotyping in a large, unselected population of women in midgestation to identify similarities and differences in cardiovascular adaptation in women who are at risk of GDM and/or HDP.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 19 + 1 to 23 + 3 weeks' gestation. This visit included assessment of flow velocity waveforms from the maternal ophthalmic arteries, echocardiography for assessment of maternal cardiovascular function and measurement of uterine artery pulsatility index and serum placental growth factor (PlGF) for assessment of placental perfusion and function. The measured indices were converted to either multiples of the median (MoM) values or deviation from the median (delta) after adjusting for maternal characteristics and elements of medical history. Biomarker delta or MoM values in the GDM and HDP groups were compared with those in the unaffected group using 95% CI and t-tests.

RESULTS

The study population of 5214 pregnancies contained 4429 (84.9%) that were unaffected by GDM or HDP, 509 (9.8%) complicated by GDM without HDP, 41 (0.8%) with GDM and HDP, and 235 (4.5%) with HDP without GDM. In HDP cases, with or without GDM, there was evidence of impaired placentation, with a decrease in PlGF, and increased impedance to flow in the peripheral circulation, suggested by an increase in ophthalmic artery peak systolic velocity (PSV) ratio, peripheral vascular resistance assessed on echocardiography and mean arterial pressure. In the GDM group without HDP, there was no evidence of altered placental perfusion or function and ophthalmic artery PSV ratio was not significantly different from that in the unaffected group; peripheral vascular resistance and mean arterial pressure were increased but to a lesser degree than in the HDP group. In the HDP group, there was an increase in global longitudinal systolic strain and slight increase in isovolumic relaxation time, while in the GDM group, there was an increase in mitral valve E/e', myocardial performance index and global longitudinal systolic strain.

CONCLUSIONS

In midgestation, women who subsequently develop HDP or GDM have a mild subclinical reduction in left ventricular function. In HDP cases, with or without GDM, there is evidence of impaired placentation and all biomarkers of impedance to peripheral blood flow are consistently increased. In contrast, in the GDM group without HDP, biomarkers of placental function are normal and those of impedance to peripheral blood flow are either marginally increased or not significantly different from those in normal pregnancies. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler at 19-23 weeks' gestation in pregnancies that deliver small-for-gestational-age neonates

OBJECTIVES

First, to explore hemodynamic differences between pregnancies delivering a small-for-gestational-age (SGA) neonate in the absence of hypertensive disorders and those that develop pre-eclampsia (PE) or gestational hypertension (GH), by comparing the ophthalmic artery peak systolic velocity (PSV) ratio and first (PSV1) and second (PSV2) PSV at 19-23 weeks' gestation, and second, to compare these pregnancies for markers of placental perfusion and function.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 19 + 1 to 23 + 3 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination for assessment of fetal anatomy and growth, and measurement of maternal ophthalmic artery PSV ratio, PSV1, PSV2, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI) and serum placental growth factor (PlGF). The values of PSV ratio, PSV1, PSV2, MAP, UtA-PI and PlGF were converted to multiples of the median (MoM) or deltas. Mean MoMs or deltas of these biomarkers in the SGA, PE and GH groups were compared with those in the unaffected group. The definition of SGA was birth weight below the 10^th percentile in the absence of PE or GH.

RESULTS

The study population of 5214 pregnancies contained 4375 (83.9%) that were unaffected by SGA, PE or GH, 563 (10.8%) complicated by SGA, 157 (3.0%) with PE and 119 (2.3%) with GH. There were three main findings of the study. First, in the SGA, PE and GH groups, compared with unaffected pregnancies, the PSV ratio delta, PSV2 MoM, MAP MoM and UtA-PI MoM were increased and PlGF MoM was decreased; however, the magnitude of most changes was smaller in the SGA group than in PE and GH groups. Second, in the PE and GH groups, but not in the SGA group, PSV1 MoM was increased. Third, in general, in the pathological pregnancies, the magnitude of deviation of biomarkers from unaffected pregnancies was greater for those delivering at < 37 than at ≥ 37 weeks' gestation.

CONCLUSION

In mid-gestation, pregnancies that subsequently develop hypertensive disorders and those delivering a SGA neonate, compared with unaffected pregnancies, have abnormal uteroplacental measurements and increased maternal ophthalmic artery PSV ratio. These data suggest similar pathophysiology in the two conditions, with evidence of placental dysfunction and increased peripheral vascular resistance, but the magnitude of abnormalities is greater in hypertensive disorders. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler at 11-13 weeks' gestation in prediction of pre-eclampsia

OBJECTIVES

To examine the potential value of maternal ophthalmic artery Doppler at 11-13 weeks' gestation, alone and in combination with the established first-trimester biomarkers of pre-eclampsia (PE), including uterine artery pulsatility index (UtA-PI), mean arterial pressure (MAP), serum placental growth factor (PlGF) and serum pregnancy-associated plasma protein-A (PAPP-A), in the prediction of subsequent development of PE.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 11 + 0 to 13 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination for fetal anatomy and growth, assessment of flow velocity waveforms from the maternal ophthalmic arteries and calculation of the second-to-first peak systolic velocity (PSV) ratio, and measurement of MAP and serum PAPP-A. In addition, a case-control study was carried out for measurement of PlGF in stored samples from cases that developed PE and unaffected controls. The values of PSV ratio, UtA-PI, MAP, PAPP-A and PlGF were converted to multiples of the median or deltas to remove the effects of maternal characteristics and medical history. The competing-risks model was used to estimate the individual patient-specific risk of delivery with PE at < 37 and < 41 + 3 weeks' gestation for various combinations of markers. Performance was assessed using detection rates, at a fixed false-positive rate (FPR), and areas under the receiver-operating-characteristics curves. Modeled performance was also assessed.

RESULTS

The study population of 4066 pregnancies contained 114 (2.8%) that developed PE, including 25 (0.6%) that delivered with PE at < 37 weeks' gestation. The PSV ratio was significantly increased in PE pregnancies, and the effect of PE depended on gestational age at delivery, with the deviation from normal being greater for early than for late PE. Modeling demonstrated that the addition of PSV ratio improved the detection rate, at a 10% FPR, of preterm PE provided by maternal risk factors alone (from 46.3% to 58.4%), maternal factors, MAP and UtA-PI (65.9% to 70.6%), and maternal factors, MAP, UtA-PI and PlGF (74.6% to 76.7%). The PSV ratio did not improve the prediction of term PE provided by any combination of biomarkers.

CONCLUSION

Ophthalmic artery PSV ratio at 11-13 weeks' gestation is a potentially useful biomarker for prediction of subsequent development of preterm PE, but larger studies are needed to validate this finding. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Comparison of ophthalmic artery Doppler with PlGF and sFlt-1/PlGF ratio at 35-37 weeks' gestation in prediction of imminent pre-eclampsia

OBJECTIVE

To compare the predictive performance for delivery with pre-eclampsia (PE) at < 3 weeks and at any stage after assessment at 35 + 0 to 36 + 6 weeks' gestation of serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1)/PlGF ratio with that of a competing-risks model utilizing maternal risk factors, mean arterial pressure (MAP) and ophthalmic artery peak systolic velocity (PSV) ratio.

METHODS

This was a prospective observational study of women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination of fetal anatomy and growth, assessment of flow velocity waveforms from the maternal ophthalmic arteries and measurement of MAP, serum PlGF and serum sFlt-1. The performance of screening for delivery with PE at < 3 weeks and at any time after the examination was assessed using areas under the receiver-operating-characteristics curves and detection rates (DRs), at a 10% false-positive rate (FPR). McNemar's test was used to compare DRs, at a 10% FPR, between screening by PlGF concentration, the sFlt-1/PlGF concentration ratio and the competing-risks model utilizing maternal risk factors, MAP and ophthalmic artery PSV ratio. Model-based estimates of screening performance for different methods of screening were also produced.

RESULTS

The study population of 2338 pregnancies contained 75 (3.2%) cases that developed PE, including 30 (1.3%) that delivered with PE at < 3 weeks from assessment, and 2263 cases unaffected by PE. The DR of PE at < 3 weeks from assessment, at a 10% FPR, of sFlt-1/PlGF ratio (70.0% (95% CI, 50.6-85.3%)) was superior to that of PlGF (50.0% (95% CI, 31.3-68.7%)) or PSV ratio (56.7% (95% CI, 37.4-74.5%)) but inferior to that of the combination of maternal risk factors, MAP multiples of the median (MoM) and PSV ratio delta (96.7% (95% CI, 82.8-99.9%)). Similarly, the DR of PE at any stage after assessment of sFlt-1/PlGF ratio (62.7% (95% CI, 50.7-73.6%)) was superior to that of PlGF (52.0% (95% CI, 40.2-63.7%)) or PSV ratio (41.3% (95% CI, 30.1-53.3%)) but inferior to that of the combination of maternal risk factors, MAP MoM and PSV ratio delta (78.7% (95% CI, 67.7-87.3%)). The empirical results for DR at a 10% FPR were consistent with the modeled results, both for delivery with PE at < 3 weeks and at any time after assessment.

CONCLUSION

Ophthalmic artery Doppler in combination with maternal risk factors and blood pressure could potentially replace measurement of PlGF and sFlt-1/PlGF ratio in the prediction of imminent PE. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Maternal cardiac function in twin pregnancy at 19-23 weeks' gestation

OBJECTIVES

To compare maternal cardiovascular indices at 19-23 weeks' gestation between twin and singleton pregnancies and assess the impact of chorionicity on these parameters.

METHODS

This was a prospective observational study in women with twin pregnancy attending for a hospital visit at 19 + 1 to 24 + 3 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history and maternal cardiovascular assessment. In a previous study of 4795 women with singleton pregnancies at 19-23 weeks' gestation, multivariable linear regression models were fitted between the various cardiovascular indices and elements of maternal characteristics and medical history. In this study, we calculated multiples of the median (MoM) and delta values according to the singleton models and assessed the distributional properties of these MoM and delta values in twin as compared with singleton pregnancies.

RESULTS

The study population of 155 women with twin pregnancy included 86 dichorionic and 69 monochorionic cases. In general, there was a similar distribution of maternal cardiovascular indices in monochorionic and dichorionic twin pregnancies. In both types of twin pregnancy, compared with singleton pregnancy, there was an increase in isovolumetric relaxation time, left atrial area and myocardial performance index, and a decrease in mitral valve E/A. Left ventricular mass indexed for body surface area and relative wall thickness were also increased in twin compared with singleton pregnancy. The magnitude of the increase in left atrial area was greater in dichorionic compared with monochorionic pregnancies. Additionally, mitral valve E was decreased and left atrial volume was increased in dichorionic but not in monochorionic pregnancies, while isovolumetric contraction time was increased in monochorionic but not in dichorionic pregnancies. Left ventricular myocardial deformation was similar between twin and singleton pregnancies.

CONCLUSIONS

In twin pregnancies at mid-gestation, maternal systolic and diastolic function is reduced when compared with singletons. The patterns of cardiovascular adaptation are similar between monochorionic and dichorionic pregnancies and resemble those reported in uncomplicated singleton pregnancy later in gestation. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Ophthalmic artery Doppler at 35-37 weeks' gestation in pregnancies with small or growth-restricted fetuses

OBJECTIVES

First, to compare the ophthalmic artery peak systolic velocity (PSV) ratio at 35-37 weeks' gestation among women who delivered small-for-gestational-age (SGA) or growth-restricted (FGR) neonates in the absence of hypertensive disorders, women who developed pre-eclampsia (PE) or gestational hypertension (GH) and those without SGA, FGR, PE or GH. Second, to examine the association of PSV ratio with placental growth factor (PlGF) and mean arterial pressure (MAP). Third, to assess the associations of PSV ratio, PlGF and MAP with birth-weight Z-score and percentile.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 35 + 0 to 36 + 6 weeks' gestation. This visit included recording of maternal demographic characteristics and medical history, ultrasound examination of fetal anatomy and growth, and measurement of maternal ophthalmic artery PSV ratio, first (PSV1) and second (PSV2) peaks of systolic velocity, MAP and serum PlGF. The values of PSV ratio, MAP and PlGF were converted to multiples of the median (MoM) or delta values, and the median MoM or delta of these variables in the SGA, FGR, PE and GH groups were compared with those in the unaffected group. Regression analysis was used to examine the relationship of PSV ratio delta, PlGF MoM and MAP MoM with birth-weight Z-score after exclusion of PE and GH cases. Regression analysis was also used to examine the association of PSV ratio delta with log₁₀ PlGF MoM and log₁₀ MAP MoM.

RESULTS

The study population included 2287 pregnancies, of which 1954 (85.4%) were not affected by FGR, SGA, PE or GH, 49 (2.1%) were complicated by FGR in the absence of PE or GH, 160 (7.0%) had SGA in the absence of FGR, PE or GH, 60 (2.6%) had PE and 64 (2.8%) had GH. Compared with unaffected pregnancies, in both the FGR and SGA groups, the means of PSV ratio delta (0.042 (95% CI, 0.007-0.076) and 0.032 (95% CI, 0.016-0.049), respectively) and MAP MoM (1.028 (95% CI, 1.006-1.050) and 1.048 (95% CI, 1.035-1.060), respectively) were increased, while the mean of PlGF MoM was decreased (0.495 (95% CI, 0.393-0.622) and 0.648 (95% CI, 0.562-0.747), respectively). However, the magnitude of these changes was smaller than in the PE and GH groups. Ophthalmic artery waveform analysis revealed that the predominant feature of pregnancies complicated by SGA in the absence of hypertensive disorders was a reduction in PSV1, whereas, in those with hypertensive disorders, there was an increase in PSV2. In non-hypertensive pregnancies, there were linear inverse associations of PSV ratio delta and MAP MoM with birth-weight Z-score, with increased values in small neonates and decreased values in large neonates. There was a quadratic relationship between PlGF MoM and birth-weight Z-score, with low PlGF levels in small neonates and high PlGF levels in large neonates. There was a significant correlation of ophthalmic artery PSV ratio delta with both log₁₀ MAP MoM (0.124 (95% CI, 0.069-0.178)) and log₁₀ PlGF MoM (-0.238 (95% CI, -0.289 to -0.185)).

CONCLUSION

Assuming that the ophthalmic artery PSV ratio is a reflection of the interplay between cardiac output and peripheral vascular resistance, the linear association between PSV ratio and birth-weight Z-score in non-hypertensive pregnancies suggests the presence of a continuous physiological relationship between fetal size and cardiovascular response rather than a dichotomous relationship between high peripheral resistance and low cardiac output in small compared with non-small fetuses. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Estimated fetal weight at mid-gestation in prediction of pre-eclampsia in singleton pregnancy

OBJECTIVE

To examine the distribution of birth weight according to gestational age in pregnancies complicated by pre-eclampsia (PE) and assess the potential value of sonographic estimated fetal weight (EFW) at mid-gestation as a predictor of PE.

METHODS

The data for this study were derived from prospective screening for adverse obstetric outcome in 93 911 women with a singleton pregnancy attending for routine pregnancy care at 19 + 0 to 24 + 6 weeks' gestation in two UK maternity hospitals. This visit included recording of maternal demographic characteristics and medical history, sonographic EFW and measurement of mean arterial pressure (MAP) and uterine artery pulsatility index (UtA-PI). The distribution of birth weight of pregnancies with and those without PE was assessed. The competing-risks model was used to estimate the individual, patient-specific risk of delivery with PE at < 32 and < 37 weeks' gestation and at any gestational age. The areas under the receiver-operating-characteristics curves and detection rates (DRs) of delivery with PE, at a 10% false-positive rate (FPR), were assessed for various combinations of maternal risk factors, EFW, MAP and UtA-PI. McNemar's test was used to determine the significance of difference in DR at a 10% FPR between screening with vs without EFW.

RESULTS

The study population contained 2843 (3.0%) pregnancies that subsequently developed PE, including 148 (0.2%) that delivered with PE at < 32 weeks' gestation and 654 (0.7%) that delivered with PE at < 37 weeks. Birth weight was < 10^th percentile in 82% of pregnancies with PE delivering at < 32 weeks' gestation and this decreased to 21% of those with PE delivering at ≥ 37 weeks. In screening for delivery with PE at < 32 and < 37 weeks' gestation, the DR, at a 10% FPR, achieved by maternal risk factors (51% and 46%, respectively) was improved by addition of EFW (69% and 51%, respectively). Similarly, addition of EFW improved the performance of screening by a combination of maternal risk factors and MAP from 72% to 80% for PE < 32 weeks and from 57% to 60% for PE < 37 weeks. EFW did not improve the predictive performance of screening by a combination of maternal risk factors, MAP and UtA-PI.

CONCLUSIONS

In pregnancies complicated by preterm PE, a high proportion of neonates are small-for-gestational age, and sonographic EFW at mid-gestation can improve the prediction of early and preterm PE provided by maternal risk factors and MAP but not the prediction provided by a combination of maternal risk factors, MAP and UtA-PI. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Changes in ophthalmic artery Doppler during acute blood-pressure control in hypertensive pregnant women

OBJECTIVE

To examine the changes in ophthalmic artery Doppler indices and their association with changes in mean arterial blood pressure (MAP) and systolic (SBP) and diastolic (DBP) blood pressure, following acute antihypertensive treatment in women with hypertensive disorders of pregnancy presenting with high blood pressure.

METHODS

This was a prospective cohort study of 31 pregnant women presenting at 30 + 0 to 39 + 6 weeks' gestation for management of their hypertension. Paired maternal blood-pressure and ophthalmic-artery-Doppler measurements were performed prior to and at 30 min and 60 min after starting antihypertensive medication. In patients who did not achieve blood-pressure control (i.e. when blood pressure was < 140/90 mmHg) by 60 min, paired readings were continued up to 120 min. If blood-pressure control was still not achieved at that point, patients were admitted to hospital. Univariate linear regression was performed to determine the association of ophthalmic artery peak systolic velocity (PSV) ratio with SBP, DBP and MAP before treatment and after blood-pressure control. The longitudinal changes in MAP, SBP, DBP and PSV ratio from pretreatment to 30 min and 60 min after commencement of antihypertensives were examined by repeated measure, multilevel, linear mixed-effects analysis.

RESULTS

Antihypertensive treatment was associated with a decrease in SBP, DBP, MAP and PSV ratio. At 60 min following antihypertensive treatment, the decrease in SBP, DBP, MAP and PSV ratio was 12.1 mmHg (95% CI, 9.0-15.1 mmHg; P < 0.0001), 9.1 mmHg (95% CI, 6.5-11.5 mmHg; P < 0.0001), 10.0 mmHg (95% CI, 7.6-12.4 mmHg; P < 0.0001) and 0.07 (95% CI, 0.03-0.11 mmHg; P < 0.001), respectively. From the total cohort, 20 (64.5%) women had achieved blood-pressure control at 60 min and another seven (22.6%) by 120 min from commencement of antihypertensive treatment. Four (12.9%) women did not achieve blood-pressure control during this period and were admitted to hospital. The relationship between PSV ratio and SBP, DBP and MAP was assessed before treatment (n = 31) and at the point of blood-pressure control in women in whom this was achieved by 120 min (n = 27). Prior to treatment, there was a significant association between PSV ratio and MAP (P < 0.0001, R²  = 0.39). This was primarily due to the association of PSV ratio with DBP (P < 0.0001, R²  = 0.39) and less so due to its association with SBP (P = 0.02, R²  = 0.16). At the point of achieving blood-pressure control, there was no significant association between PSV ratio and MAP (P = 0.7), DBP (P = 0.5) or SBP (P = 0.7).

CONCLUSIONS

Acute blood-pressure control in pregnancy is associated with a concomitant reduction in blood pressure and ophthalmic artery PSV ratio. In hypertensive pregnant women, there is a significant association of PSV ratio with MAP, SBP and DBP, which disappears after blood pressure is reduced to < 140/90 mmHg following antihypertensive treatment. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Second-trimester contingent screening for small-for-gestational-age neonate

OBJECTIVES

First, to investigate the additive value of second-trimester placental growth factor (PlGF) for the prediction of a small-for-gestational-age (SGA) neonate. Second, to examine second-trimester contingent screening strategies.

METHODS

This was a prospective observational study in women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. We used the competing-risks model for prediction of SGA. The parameters for the prior model and the likelihoods for estimated fetal weight (EFW) and uterine artery pulsatility index (UtA-PI) were those presented in previous studies. A folded-plane regression model was fitted in the dataset of this study to describe the likelihood of PlGF. We compared the prediction of screening by maternal risk factors against the prediction provided by a combination of maternal risk factors, EFW, UtA-PI and PlGF. We also examined the additive value of PlGF in a policy that uses maternal risk factors, EFW and UtA-PI.

RESULTS

The study population included 40 241 singleton pregnancies. Overall, the prediction of SGA improved with increasing degree of prematurity, with increasing severity of smallness and in the presence of coexisting pre-eclampsia. The combination of maternal risk factors, EFW, UtA-PI and PlGF improved significantly the prediction provided by maternal risk factors alone for all the examined cut-offs of birth weight and gestational age at delivery. Screening by a combination of maternal risk factors and serum PlGF improved the prediction of SGA when compared to screening by maternal risk factors alone. However, the incremental improvement in prediction was decreased when PlGF was added to screening by a combination of maternal risk factors, EFW and UtA-PI. If first-line screening for a SGA neonate with birth weight < 10^th percentile delivered at < 37 weeks' gestation was by maternal risk factors and EFW, the same detection rate of 90%, at an overall false-positive rate (FPR) of 50%, as that achieved by screening with maternal risk factors, EFW, UtA-PI and PlGF in the whole population can be achieved by reserving measurements of UtA-PI and PlGF for only 80% of the population. Similarly, in screening for a SGA neonate with birth weight < 10^th percentile delivered at < 30 weeks, the same detection rate of 90%, at an overall FPR of 14%, as that achieved by screening with maternal risk factors, EFW, UtA-PI and PlGF in the whole population can be achieved by reserving measurements of UtA-PI and PlGF for only 70% of the population. The additive value of PlGF in reducing the FPR to about 10% with a simultaneous detection rate of 90% for a SGA neonate with birth weight < 3^rd percentile born < 30 weeks, is gained by measuring PlGF in only 50% of the population when first-line screening is by maternal factors, EFW and UtA-PI.

CONCLUSIONS

The combination of maternal risk factors, EFW, UtA-PI and PlGF provides effective second-trimester prediction of SGA. Serum PlGF is useful for predicting a SGA neonate with birth weight < 3^rd percentile born < 30 weeks after an inclusive assessment by maternal risk factors and biophysical markers. Similar detection rates and FPRs can be achieved by application of contingent screening strategies. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Risk of fetal loss after chorionic villus sampling in twin pregnancy derived from propensity score matching analysis

OBJECTIVE

To estimate the risk of fetal loss associated with chorionic villus sampling (CVS) in twin pregnancy, using propensity score analysis.

METHODS

This was a multicenter cohort study of women with twin pregnancy undergoing ultrasound examination at 11-13 weeks' gestation, performed in eight fetal medicine units in which the leadership were trained at the Harris Birthright Research Centre for Fetal Medicine in London, UK, and in which the protocols for screening, invasive testing and pregnancy management are similar. The risk of death of at least one fetus was compared between pregnancies that had and those that did not have CVS, after propensity score matching (1:1 ratio). This procedure created two comparable groups by balancing the maternal and pregnancy characteristics that lead to CVS being performed, similar to how randomization operates in a randomized clinical trial.

RESULTS

The study population of 8581 twin pregnancies included 445 that had CVS. Death of one or two fetuses at any stage during pregnancy occurred in 11.5% (51/445) of pregnancies in the CVS group and in 6.3% (515/8136) in the non-CVS group (P < 0.001). The propensity score algorithm matched 258 cases that had CVS with 258 non-CVS cases; there was at least one fetal loss in 29 (11.2%) cases in the CVS group and in 35 (13.6%) cases in the matched non-CVS group (odds ratio (OR), 0.81; 95% CI, 0.48-1.35; P = 0.415). However, there was a significant interaction between the risk of fetal loss after CVS and the background risk of fetal loss; when the background risk was higher, the risk of fetal loss after CVS decreased (OR, 0.46; 95% CI, 0.23-0.90), while, in pregnancies with a lower background risk of fetal loss, the risk of fetal loss after CVS increased (OR, 2.45; 95% CI, 0.95-7.13). The effects were statistically significantly different (P-value of the interaction = 0.005). For a pregnancy in which the background risk of fetal loss was about 6% (the same as in our non-CVS population), there was no change in the risk of fetal loss after CVS, but, when the background risk was more than 6%, the posterior risk was paradoxically reduced, and when the background risk was less than 6%, the posterior risk increased exponentially; for example, if the background risk of fetal loss was 2.0%, the relative risk was 2.8 and the posterior risk was 5.6%.

CONCLUSION

In twin pregnancy, after accounting for the risk factors that lead to both CVS and spontaneous fetal loss and confining the analysis to pregnancies at lower prior risk, CVS seems to increase the risk of fetal loss by about 3.5% above the patient's background risk. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Development and validation of model for prediction of placental dysfunction-related stillbirth from maternal factors, fetal weight and uterine artery Doppler at mid-gestation

OBJECTIVE

To examine the performance of a model combining maternal risk factors, uterine artery pulsatility index (UtA-PI) and estimated fetal weight (EFW) at 19-24 weeks' gestation, for predicting all antepartum stillbirths and those due to impaired placentation, in a training dataset used for development of the model and in a validation dataset.

METHODS

The data for this study were derived from prospective screening for adverse obstetric outcome in women with singleton pregnancy attending for routine pregnancy care at 19 + 0 to 24 + 6 weeks' gestation. The study population was divided into a training dataset used to develop prediction models for placental dysfunction-related antepartum stillbirth and a validation dataset to which the models were then applied. Multivariable logistic regression analysis was used to develop a model based on a combination of maternal risk factors, EFW Z-score and UtA-PI multiples of the normal median. We examined the predictive performance of the model by, first, the ability of the model to discriminate between the stillbirth and live-birth groups, using the area under the receiver-operating-characteristics curve (AUC) and the detection rate (DR) at a fixed false-positive rate (FPR) of 10%, and, second, calibration by measurements of calibration slope and intercept.

RESULTS

The study population of 131 514 pregnancies included 131 037 live births and 477 (0.36%) stillbirths. There are four main findings of this study. First, 92.5% (441/477) of stillbirths were antepartum and 7.5% (36/477) were intrapartum, and 59.2% (261/441) of antepartum stillbirths were observed in association with placental dysfunction and 40.8% (180/441) were unexplained or due to other causes. Second, placental dysfunction accounted for 80.1% (161/201) of antepartum stillbirths at < 32 weeks' gestation, 54.2% (52/96) at 32 + 0 to 36 + 6 weeks and 33.3% (48/144) at ≥ 37 weeks. Third, the risk of placental dysfunction-related antepartum stillbirth increased with increasing maternal weight and decreasing maternal height, was 3-fold higher in black than in white women, was 5.5-fold higher in parous women with previous stillbirth than in those with previous live birth, and was increased in smokers, in women with chronic hypertension and in parous women with a previous pregnancy complicated by pre-eclampsia and/or birth of a small-for-gestational-age baby. Fourth, in screening for placental dysfunction-related antepartum stillbirth by a combination of maternal risk factors, EFW and UtA-PI in the validation dataset, the DR at a 10% FPR was 62.3% (95% CI, 57.2-67.4%) and the AUC was 0.838 (95% CI, 0.799-0.878); these results were consistent with those in the dataset used for developing the algorithm and demonstrate high discrimination between affected and unaffected pregnancies. Similarly, the calibration slope was 1.029 and the intercept was -0.009, demonstrating good agreement between the predicted risk and observed incidence of placental dysfunction-related antepartum stillbirth. The performance of screening was better for placental dysfunction-related antepartum stillbirth at < 37 weeks' gestation compared to at term (DR at a 10% FPR, 69.8% vs 29.2%).

CONCLUSIONS

Screening at mid-gestation by a combination of maternal risk factors, EFW and UtA-PI can predict a high proportion of placental dysfunction-related stillbirths and, in particular, those that occur preterm. Such screening provides poor prediction of unexplained stillbirth or stillbirth due to other causes. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

STATIN trial: predictive performance of competing-risks model in screening for pre-eclampsia at 35-37 weeks' gestation

OBJECTIVE

To examine the predictive performance of a previously reported competing-risks model of screening for pre-eclampsia (PE) at 35-37 weeks' gestation by combinations of maternal risk factors, mean arterial pressure (MAP), uterine artery pulsatility index (UtA-PI), serum placental growth factor (PlGF) and serum soluble fms-like tyrosine kinase-1 (sFlt-1) in a validation dataset derived from the screened population of the STATIN study.

METHODS

This was a prospective third-trimester multicenter study of screening for PE in singleton pregnancies by means of a previously reported algorithm that combines maternal risk factors and biomarkers. Women in the high-risk group were invited to participate in a trial of pravastatin vs placebo, but the trial showed no evidence of an effect of pravastatin in the prevention of PE. Patient-specific risks of delivery with PE were calculated using the competing-risks model, and the performance of screening for PE by maternal risk factors alone and by various combinations of risk factors with MAP, UtA-PI, PlGF and sFlt-1 was assessed. The predictive performance of the model was examined by, first, the ability of the model to discriminate between the PE and no-PE groups using the area under the receiver-operating-characteristics curve (AUC) and the detection rate at a fixed false-positive rate of 10%, and, second, calibration by measurements of calibration slope and calibration-in-the-large.

RESULTS

The study population of 29 677 pregnancies contained 653 that developed PE. In screening for PE by a combination of maternal risk factors, MAP, PlGF and sFlt-1 (triple test), the detection rate at a 10% false-positive rate was 79% (95% CI, 76-82%) and the results were consistent with the data used for developing the algorithm. Addition of UtA-PI did not improve the prediction provided by the triple test. The AUC for the triple test was 0.923 (95% CI, 0.913-0.932), demonstrating very high discrimination between affected and unaffected pregnancies. Similarly, the calibration slope was 0.875 (95% CI, 0.831-0.919), demonstrating good agreement between the predicted risk and observed incidence of PE.

CONCLUSION

The competing-risks model provides an effective and reproducible method for third-trimester prediction of term PE. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Percutaneous fetoscopic spina bifida repair: effect on ambulation and need for postnatal cerebrospinal fluid diversion and bladder catheterization

OBJECTIVE

A trial comparing prenatal with postnatal open spina bifida (OSB) repair established that prenatal surgery was associated with better postnatal outcome. However, in the trial, fetal surgery was carried out through hysterotomy. Minimally invasive approaches are being developed to mitigate the risks of open maternal-fetal surgery. The objective of this study was to investigate the impact of a novel neurosurgical technique for percutaneous fetoscopic repair of fetal OSB, the skin-over-biocellulose for antenatal fetoscopic repair (SAFER) technique, on long-term postnatal outcome.

METHODS

This study examined descriptive data for all patients undergoing fetoscopic OSB repair who had available 12- and 30-month follow-up data for assessment of need for cerebrospinal fluid (CSF) diversion and need for bladder catheterization and ambulation, respectively, from eight centers that perform prenatal OSB repair via percutaneous fetoscopy using a biocellulose patch between the neural placode and skin/myofascial flap, without suture of the dura mater (SAFER technique). Univariate and multivariate logistic regression analyses were used to examine the effect of different factors on need for CSF diversion at 12 months and ambulation and need for bladder catheterization at 30 months. Potential cofactors included gestational age at fetal surgery and delivery, preoperative ultrasound findings of anatomical level of the lesion, cerebral lateral ventricular diameter, lesion type and presence of bilateral talipes, as well as postnatal findings of CSF leakage at birth, motor level, presence of bilateral talipes and reversal of hindbrain herniation.

RESULTS

A total of 170 consecutive patients with fetal OSB were treated prenatally using the SAFER technique. Among these, 103 babies had follow-up at 12 months of age and 59 had follow-up at 30 months of age. At 12 months of age, 53.4% (55/103) of babies did not require ventriculoperitoneal shunt or third ventriculostomy. At 30 months of age, 54.2% (32/59) of children were ambulating independently and 61.0% (36/59) did not require chronic intermittent catheterization of the bladder. Multivariate logistic regression analysis demonstrated that significant prediction of need for CSF diversion was provided by lateral ventricular size and type of lesion (myeloschisis). Significant predictors of ambulatory status were prenatal bilateral talipes and anatomical and functional motor levels of the lesion. There were no significant predictors of need for bladder catheterization.

CONCLUSION

Children who underwent prenatal OSB repair via the percutaneous fetoscopic SAFER technique achieved long-term neurological outcomes similar to those reported in the literature after hysterotomy-assisted OSB repair. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Contingent screening in stratification of pregnancy care based on risk of pre-eclampsia at 19-24 weeks' gestation

OBJECTIVE

To explore the possibility of carrying out routine screening for pre-eclampsia (PE) with delivery at < 28, < 32, < 36 weeks' gestation by maternal factors, uterine artery pulsatility index (UtA-PI) and mean arterial pressure (MAP) in all pregnancies and reserving measurements of placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) for only a subgroup of the population.

METHODS

This was a prospective observational study in two UK maternity hospitals involving women with singleton pregnancy attending for routine assessment at 19-24 weeks' gestation. The improvement in performance of screening for PE, at fixed risk cut-offs, by the addition of serum PlGF and sFlt-1 to screening by maternal factors, UtA-PI and MAP, was estimated. We examined a policy of contingent screening in which biochemical testing was reserved for only a subgroup of the population. The main outcome measures were the additional contribution of PlGF and sFlt-1 to the performance of screening for PE and the proportion of the population requiring measurement of PlGF and sFlt-1 for maximum performance of screening.

RESULTS

The study population included 37 886 singleton pregnancies. At each risk cut-off, the highest detection rates for delivery with PE and the lowest screen-positive rates were achieved in screening with maternal factors, UtA-PI, MAP, PlGF and sFlt-1. The maximum performance by such screening was also achieved by contingent screening in which PlGF and sFlt-1 were measured in only about 40% of the population.

CONCLUSION

The performance of screening for PE by a combination of maternal factors, UtA-PI and MAP is improved by measurement of PlGF and sFlt-1 in about 40% of the population. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.