Prediction of small-for-gestational-age neonates: screening by uterine artery Doppler and mean arterial pressure at 30-34 weeks

Fetal Growth Restriction Is Associated with Pregnancy Associated Plasma Protein A and Uterine Artery Doppler in First Trimester

Fetal growth restriction (FGR) is a major cause of stillbirth and poor neurodevelopmental outcomes. The early prediction may be important to establish treatment options and improve neonatal outcomes. The aim of this study was to assess the association of parameters used in first-trimester screening, uterine artery Doppler pulsatility index and the development of FGR. In this retrospective cohort study, 1930 singleton pregnancies prenatally diagnosed with an estimated fetal weight under the third percentile were included. All women underwent first-trimester screening assessing maternal serum pregnancy-associated plasma protein A (PAPP-A), free beta-human chorionic gonadotrophin levels, fetal nuchal translucency and uterine artery Doppler pulsatility index (PI). We constructed a Receiver Operating Characteristics curve to calculate the sensitivity and specificity of early diagnosis of FGR. In pregnancies with FGR, PAPP-A was significantly lower, and uterine artery Doppler pulsatility index was significantly higher compared with the normal birth weight group (0.79 ± 0.38 vs. 1.15 ± 0.59, p < 0.001 and 1.82 ± 0.7 vs. 1.55 ± 0.47, p = 0.01). Multivariate logistic regression analyses demonstrated that PAPP-A levels and uterine artery Doppler pulsatility index were significantly associated with FGR (p = 0.009 and p = 0.01, respectively). To conclude, these two parameters can predict FGR < 3rd percentile.

Third trimester uterine artery Doppler for prediction of adverse perinatal outcomes

PURPOSE OF REVIEW

Abnormal uterine artery Doppler (UtAD) studies early in gestation have been associated with adverse pregnancy outcomes. However, their association with complications in the third trimester is weak. We aim to review the prediction ability for perinatal complications of these indices in the third trimester.

RECENT FINDINGS

Abnormal UtAD waveforms in the third trimester are associated with preeclampsia, small-for-gestational age infants (SGA), preterm birth, perinatal death, and other perinatal complications, such as cesarean section for fetal distress, 5 min low Apgar score, low umbilical artery pH, and neonatal admission to the ICU, particularly in SGA infants. UtAD prediction performance is improved by the addition of maternal characteristics as well as biochemical markers to prediction models and is more precise if the evaluation is made closer to delivery or diagnosis.

SUMMARY

This review shows that the prediction accuracy of UtAD for adverse pregnancy outcomes during the third trimester is moderate at best. UtAD have limited additive value to prediction models that include PlGF and sFlt-1. Serial assessments rather than a single third trimester evaluation may enhance the prediction performance of the UtAD combined models.

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 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.

Adverse perinatal outcomes in fetuses with severe late-onset fetal growth restriction

OBJECTIVE

To evaluate perinatal outcomes in fetuses with severe late-onset fetal growth restriction.

METHODS

This was a retrospective and observational cohort study in which pregnant women diagnosed with late-onset fetal growth restriction assisted at perinatal maternity birth from 2010 to 2017 were included. The outcomes were intensive care unit (ICU) admission and perinatal complications, such as neonatal death, intraventricular hemorrhage, periventricular leukomalacia, hypoxic-ischemic encephalopathy, necrotizing enterocolitis, bronchopulmonary dysplasia, and sepsis.

RESULTS

We selected 277 pregnant women, of whom 124 newborns (44.76%) went to the ICU. The chance of a newborn needing ICU decreases by 62, 7, and 9% according to an increase of one gestational week, 1 cm of the abdominal circumference, or 1 cm of the amniotic fluid index, respectively. Oligohydramnios increases the risk of going to the ICU by 2.13 times. The increase in the umbilical artery pulsatility index (PI) Doppler increases the chance of ICU admission by 7.9 times. The normal middle cerebral artery PI Doppler and the normal cerebroplacental ratio reduce the risk of ICU admission.

CONCLUSION

The estimated fetal weight, abdominal circumference, and amniotic fluid index diagnosed severe late-onset fetal growth restriction. With the decrease in middle cerebral artery PI Doppler, there is a greater probability of admission to the ICU, with the most common complications being intraventricular hemorrhage and necrotizing enterocolitis.

Doppler ultrasound in pregnancy - quality requirements of DEGUM and clinical application (part 2)

This second part on Doppler sonography in prenatal medicine and obstetrics reviews its clinical applications. While this has not become the initially anticipated screening tool, it is used for the diagnosis and surveillance of a variety of fetal pathologies. For example, the sonography-based determination of uterine artery blood flow indices is an important parameter for the first trimester multimodal preeclampsia risk assessment, increasing accuracy and providing indication for the prophylactic treatment with aspirin. It also has significant implications for the diagnosis and surveillance of growth-restricted fetuses in the second and third trimesters through Doppler-sonographic analysis of umbilical artery, middle cerebral artery and ductus venosus. Here, especially the hemodynamics of the ductus venosus provides a critical criterium for birth management of severe, early-onset FGR before 34 + 0 weeks of gestation. Further, determination of maximum blood flow velocity of the middle cerebral artery is a central parameter in fetal diagnosis of anemia which has been significantly improved by this analysis. However, it is important to note that the mentioned improvements can only be achieved through highest methodological quality. Importantly, all these analyses are also applied to twins and higher order multiples. Here, for the differential diagnosis of specific complications such as TTTS, TAPS and TRAP, the application of Doppler sonography has become indispensable. To conclude, the successful application of Doppler sonography requires both exact methodology and precise pathophysiological interpretation of the data.

Increased pulsatility index of uterine artery Doppler between 26 and 28 weeks of gestation and adverse perinatal outcomes

OBJECTIVE

To compare adverse perinatal outcomes in pregnant women with or without normalization of the mean pulsatility index (PI) uterine artery Doppler between 24 and 28 weeks of gestation.

METHODS

Retrospective cohort which pregnant women were divided into three groups: normal uterine artery Doppler between 20-24 and 26-28 weeks (controls), abnormal uterine artery Doppler between 20-24 and normal between 26-28 weeks (anUtA), and abnormal uterine artery Doppler between 20-24 and 26-28 weeks (aaUtA). To compare adverse perinatal results between the groups Chi-square test was used. Binary logistic regression was used to assess the ability of uterine artery Doppler to predict birthweight < 10th and composite perinatal outcomes.

RESULTS

Birthweight was significantly lower in the aaUtA compared to anUtA (2687 vs 3248 grams, p = 0.0479). A significant negative correlation was observed between the mean PI uterine artery Doppler during the 3rd trimester and birthweight (r = -0.13, R ² = 0.035, p = .0192). The prevalence of composite perinatal outcomes was significantly higher in aaUtA compared to anUtA (25.9 vs 0%, p = .013). Mean PI uterine artery Doppler during the 3rd trimester was significant predictor for birthweight < 10th (OR: 2.74, CI 95% = 1.03-7.3), but the protodiastolic notch and the association between mean PI uterine artery Doppler and protodiastolic notch were not.

CONCLUSION

Maintenance of altered uterine artery Doppler during the 3rd trimester was associated with higher prevalence of composite perinatal outcomes and lower birthweight compared to its late normalization. Although modest, uterine artery Doppler in the 3rd trimester proved to be predictor of birthweight < 10th.

Placental transverse relaxation time (T2) estimated by MRI: Normal values and the correlation with birthweight

INTRODUCTION

Placental transverse relaxation time (T2) assessed by MRI may have the potential to improve the antenatal identification of small for gestational age. The aims of this study were to provide normal values of placental T2 in relation to gestational age at the time of MRI and to explore the correlation between placental T2 and birthweight.

MATERIAL AND METHODS

A mixed cohort of 112 singleton pregnancies was retrieved from our placental MRI research database. MRI was performed at 23.6-41.3 weeks of gestation in a 1.5T system (TE (8): 50-440 ms, TR: 4000 ms). Normal pregnancies were defined by uncomplicated pregnancies with normal obstetric outcome and birthweight deviation within ±1 SD of the expected for gestational age. The correlation between placental T2 and birthweight was investigated using the following outcomes; small for gestational age (birthweight ≤-2 SD of the expected for gestational age) and birthweight deviation (birthweight Z-scores).

RESULTS

In normal pregnancies (n = 27), placenta T2 showed a significant negative linear correlation with gestational age (r = -.91, P = .0001) being 184 ms ± 15.94 ms (mean ± SD) at 20 weeks of gestation and 89 ms ± 15.94 ms at 40 weeks of gestation. Placental T2 was significantly reduced among small-for-gestational-age pregnancies (mean Z-score -1.95, P < .001). Moreover, we found a significant positive correlation between placenta T2 deviation (Z-score) and birthweight deviation (Z-score) (R²  = .26, P = .0001).

CONCLUSIONS

This study provides normal values of placental T2 to be used in future studies on placental MRI. Placental T2 is closely related to birthweight and may improve the antenatal identification of small-for-gestational-age pregnancies.

Visit-to-visit blood pressure variability and risk of adverse birth outcomes in pregnancies in East China

To investigate the potential associations between visit-to-visit blood pressure variability (VVV) and adverse birth outcomes in pregnancies, 48,209 pregnant women without proteinuria or chronic hypertension before 20 weeks of gestation who delivered live singletons between January 2014 and November 2019 in Taizhou or Taicang cities were recruited. VVV was estimated as the standard deviation and coefficient of variation of blood pressure [i.e., systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP)] measured from 20 weeks of gestation onwards. Pregnant women were classified into four groups according to the corresponding quartiles for each VVV index. It was found that VVV was significantly higher in women with small for gestational age (SGA) or low birth weight (LBW) infants than in their counterparts. Graded associations between VVV categories and poor birth outcomes were observed. In particular, when comparing the women with the highest to the lowest quartiles of standard deviation and coefficient variation of DBP, the odds ratios (95% confidence interval) for SGA was 1.15 (1.06-1.26) and 1.14 (1.05-1.25), respectively. Interestingly, the addition of DBP-VVV to established risk factors improved risk prediction of SGA; DBP-VVV demonstrated modestly superior predictive performance to VVV obtained from SBP or MAP. Similar results were found even among normotensive pregnancies. Our findings indicated that VVV during pregnancy, especially DBP-VVV, was independently associated with poor birth outcomes of pregnancies in East China. The inclusion of DBP-VVV with established risk factors may help in identifying pregnancies at high risk of SGA. Validations are needed.

Placental diffusion-weighted MRI in normal pregnancies and those complicated by placental dysfunction due to vascular malperfusion

INTRODUCTION

Our aim was to assess placental function by diffusion-weighted magnetic resonance imaging (MRI) using intravoxel incoherent motion (IVIM) analysis in uncomplicated pregnancies and pregnancies complicated by placental dysfunction.

METHODS

31 normal pregnancies and 9 pregnancies complicated by placental dysfunction (birthweight ≤ -2SD and histological signs of placental vascular malperfusion) were retrieved from our placental MRI research database. MRI was performed at gestational weeks 20.1-40.6 in a 1.5 T system using 10 b-values (0-1000 s/mm²). Regions of interest were drawn covering the entire placenta in five transverse slices. Diffusion coefficient (D), pseudodiffusion coefficient (D*) and perfusion fraction (f) were estimated by IVIM analysis.

RESULTS

In normal pregnancies, placental f decreased linearly with gestational age (r = -0.522, p = 0.002) being 26.2% at week 20 and 18.8% at week 40. D and D* were 1.57 ± 0.03 and 31.7 ± 3.1 mm²/s (mean ± SD), respectively, and they were not correlated with gestational age. In complicated pregnancies, f was significantly reduced (mean Z-score = -1.16; p = 0.02) when compared to the group of normal pregnancies, whereas D and D* did not differ significantly between groups. Subgroup analysis demonstrated that f was predominantly reduced in dysfunctional placentas characterized by fetal vascular malperfusion (mean Z-score = -2.11, p < 0.001) rather than maternal vascular malperfusion (mean Z-score = -0.40, p = 0.42). In addition, f was negatively correlated with uterine artery pulsatility index (r = -0.396, p = 0.01).

DISCUSSION

Among parameters obtained by the IVIM analysis, only f revealed significant differences between the normal and the dysfunctional placentas. Subgroup analysis suggests that placental f may be able to discriminate non-invasively between different histological types of vascular malperfusion.

Screening for small-for-gestational-age fetuses

INTRODUCTION

It is well established that correct antenatal identification of small-for-gestational-age (SGA) fetuses reduces their risk of adverse perinatal outcome with long-term consequences. Ultrasound estimates of fetal weight (EFW_us ) are the ultimate tool for this identification. It can be conducted as a "universal screening", that is, all pregnant women at a specific gestational age. However, in Denmark it is conducted as "selective screening", that is, only on clinical indication. The aim of this study was to assess the performance of the Danish national SGA screening program and the consequences of false-positive and false-negative SGA cases.

MATERIAL AND METHODS

In this retrospective cohort study, we included 2928 women with singleton pregnancies with due dates in 2015. We defined "risk of SGA" by an EFW_us  ≤ -15% of expected for the gestational age and "SGA" as birthweight ≤-22% of expected for gestational age.

RESULTS

At birth, the prevalence of SGA was 3.3%. The overall sensitivity of the Danish screening program was 62% at a false-positive rate of 5.6%. Within the entire cohort, 63% had an EFW_us compared with 79% of the SGA cases. The sensitivity was 79% for those born before 37 weeks of gestation but only 40% for those born after 40 weeks of gestation. The sensitivity was also associated with birthweight deviation; 73% among extreme SGA cases (birthweight deviation ≤-33%) and 55% among mild SGA (birthweight deviation between -22% and -27%). False diagnosis of SGA was associated with an increased rate of induction of labor (OR_adj  = 2.51, 95% CI 1.70-3.71) and cesarean section (OR_adj  = 1.44, 95% CI 0.96-2.18).

CONCLUSIONS

The performance of the Danish national screening program for SGA based on selective EFW_us on clinical indication has improved considerably over the last 20 years. Limitations of the program are the large proportion of women referred to ultrasound scan and the low performance post-term.

Third trimester uterine artery Doppler indices as predictors of preeclampsia and neonatal small for gestational age

Objective: To test the hypothesis that third-trimester uterine artery Doppler (UAD) predicts adverse pregnancy and neonatal outcomes in a high-risk population.Study design: This is a nested case control study of women with singleton gestations referred for a fetal growth ultrasound between 24 and 36 weeks. Third-trimester UAD was performed if estimated fetal weight (Hadlock's chart) was <20th percentile as these patients were considered high risk for poor pregnancy outcomes. The primary outcomes assessed were neonatal small for gestational age (SGA) and hypertensive disorders. Secondary outcomes included pH <7.10, NICU admission, Apgar <7 at 5 minutes, respiratory distress syndrome, hypoglycemia, and a composite (presence of one or more of the secondary outcomes) neonatal adverse outcome. The sensitivity and specificity of the UAD indices for predicting these outcomes were compared.Results: Among 200 women included, neonatal SGA occurred in 91 (46%) neonates, preeclampsia in 21 (10.5%), early preeclampsia in 4 (2%) and a composite adverse outcome in 67 (34%) neonates. Abnormal UAD indices, specifically left uterine artery notching and pulsatile index (PI) >95th percentile, were significantly correlated with an increased relative risk (RR) of a number of outcomes. Left uterine artery notching was significantly associated with SGA, RR 1.76 (1.03-3.04), preeclampsia, RR 2.53 (1.47-4.37) and early preeclampsia, RR 2.88 (1.34-6.20). The PI >95th percentile was significantly associated with SGA, RR 1.83 (1.21-2.76), NICU admission, RR 1.79 (1.14-2.79), preeclampsia, RR 1.98 (1.29-3.03), and early preeclampsia, RR 3.13 (2.54-3.86). The mean UAD PI >95th percentile had the best sensitivity for SGA, but the area under the ROC curve (AUC) was modest (0.60, 95% CI = 0.53-0.67). Left uterine artery notching and PI >95th percentile had similar predictive utility for preeclampsia AUC 0.65, 95% CI = 0.53-0.76 (mean uterine artery PI >95th percentile) and AUC 0.66, 95% CI = 0.54-0.77 (left uterine artery notching).Conclusion: Abnormal third-trimester UAD indices are associated with adverse perinatal outcomes including neonatal SGA, preeclampsia, and early preeclampsia. Though statistically significantly correlated, the predictive value of UAD indices for adverse pregnancy and neonatal outcomes was modest.

The Assessment of Association between Uterine Artery Pulsatility Index at 30-34 Week's Gestation and Adverse Perinatal Outcome

Background:

Given the high prevalence of adverse perinatal outcome in the developing countries and the association between uterine artery (UtA) blood flow and fetal status in the uterine, in the current study, we assess the association between UtA pulsatility index (UtA-PI) at 30–34 week's gestation and adverse perinatal outcome.

Materials and Methods:

This cohort study included 100 pregnant women at 30–34 weeks’ gestation. At baseline, UtA-PI was evaluated with color Doppler through abdominal ultrasound. Then, adverse perinatal outcomes including preterm labor, intrauterine fetal death, preeclampsia, low 5-min Apgar score (<7), low umbilical arterial cord blood pH, admitted to Intensive Care Unit in the first 3 days of birth, low birth weight, infant with low weight, death of newborns, cesarean section for respiratory distress, and meconial amniotic fluid were recorded. Ultimately, the collected data were analyzed using SPSS, version 20.

Results:

The presence of small-for-gestational-age fetuses indicated the highest prevalent adverse prenatal outcome with the incidence of 13.3% and 58.5%, respectively, among pregnancies with normal UtA-PI as well as those with high UtA-PI (P < 0.001). Overall, given that sensitivity and specificity of high UtA-PI were 37.5% and 73.3%, respectively, it could not properly predict adverse perinatal outcome (P = 0.360).

Conclusion:

According to the results, although the incidence of some of adverse perinatal outcomes in pregnant women with high UtA-PI was higher compared to those with normal UtA-PI, this factor alone cannot predict adverse perinatal outcome well. Therefore, this factor may predict these outcomes well, in the subgroups with high-risk pregnancies or with some blood factors or with pregnancy complications.

Prediction of fetal growth restriction using estimated fetal weight vs a combined screening model in the third trimester

OBJECTIVES

To compare the performance of third-trimester screening, based on estimated fetal weight centile (EFWc) vs a combined model including maternal baseline characteristics, fetoplacental ultrasound and maternal biochemical markers, for the prediction of small-for-gestational-age (SGA) neonates and late-onset fetal growth restriction (FGR).

METHODS

This was a nested case-control study within a prospective cohort of 1590 singleton gestations undergoing third-trimester (32 + 0 to 36 + 6 weeks' gestation) evaluation. Maternal baseline characteristics, mean arterial pressure, fetoplacental ultrasound and circulating biochemical markers (placental growth factor (PlGF), lipocalin-2, unconjugated estriol and inhibin A) were assessed in all women who subsequently delivered a SGA neonate (n = 175), defined as birth weight < 10^th centile according to customized standards, and in a control group (n = 875). Among SGA cases, those with birth weight < 3^rd centile and/or abnormal uterine artery pulsatility index (UtA-PI) and/or abnormal cerebroplacental ratio (CPR) were classified as FGR. Logistic regression predictive models were developed for SGA and FGR, and their performance was compared with that obtained using EFWc alone.

RESULTS

In SGA cases, EFWc, CPR Z-score and maternal serum concentrations of unconjugated estriol and PlGF were significantly lower, while mean UtA-PI Z-score and lipocalin-2 and inhibin A concentrations were significantly higher, compared with controls. Using EFWc alone, 52% (area under receiver-operating characteristics curve (AUC), 0.82 (95% CI, 0.77-0.85)) of SGA and 64% (AUC, 0.86 (95% CI, 0.81-0.91)) of FGR cases were predicted at a 10% false-positive rate. A combined screening model including a-priori risk (maternal characteristics), EFWc, UtA-PI, PlGF and estriol (with lipocalin-2 for SGA) achieved a detection rate of 61% (AUC, 0.86 (95% CI, 0.83-0.89)) for SGA cases and 77% (AUC, 0.92 (95% CI, 0.88-0.95)) for FGR. The combined model for the prediction of SGA and FGR performed significantly better than did using EFWc alone (P < 0.001 and P = 0.002, respectively).

CONCLUSIONS

A multivariable integrative model of maternal characteristics, fetoplacental ultrasound and maternal biochemical markers modestly improved the detection of SGA and FGR cases at 32-36 weeks' gestation when compared with screening based on EFWc alone. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of low birth weight: Comparison of placental T2* estimated by MRI and uterine artery pulsatility index

OBJECTIVE

Neonates at low birth weight due to placental dysfunction are at high risk of adverse outcomes. These outcomes can be substantially improved by prenatal identification. The Magnetic Resonance Imaging (MRI) constant, placental T2* reflects placental structure and oxygenation and thereby placental function. Therefore, we aimed to evaluate the performance of placental T2* in the prediction of low birth weight using the uterine artery (UtA) pulsatility index (PI) as gold standard.

METHODS

This was a prospective observational study of 100 singleton pregnancies included at 20-40 weeks' gestation. Placental T2* was obtained using a gradient recalled multi-echo MRI sequence and UtA PI was measured using Doppler ultrasound. Placental pathological examination was performed in 57 of the pregnancies. Low birth weight was defined by a Z-score ≤ -2.0.

RESULTS

The incidence of low birth weight was 15%. The median time interval between measurements and birth was 7.3 weeks (interquartile range 3.0, 13.7 weeks). Linear regression revealed significant associations between birth weight Z-score and both placental T2* Z-score (r = 0.68, p < 0.0001) and UtA PI Z-score (r = -0.43, p < 0.0001). Receiver operating characteristic curves demonstrated a significantly higher performance of T2* (AUC of 0.92; 95% CI, 0.85-0.98) than UtA PI (AUC of 0.74; 95% CI, 0.60-0.89) in the prediction of low birth weight (p = 0.010). Placental pathological findings were closely related to the T2* values.

CONCLUSIONS

In this population, placental T2* was a strong predictor of low birth weight and it performed significantly better than the UtA PI. Thus, placental T2* is a promising marker of placental dysfunction which deserves further investigation.

Uterine artery pulsatility index at 30-34 weeks' gestation in the prediction of adverse perinatal outcome

OBJECTIVE

To investigate the potential value of uterine artery (UtA) Doppler at 30-34 weeks' gestation in the prediction of adverse perinatal outcome.

METHODS

This was a screening study in 30 780 singleton pregnancies at 30-34 weeks. UtA pulsatility index (UtA-PI) was measured and the values were converted to multiples of the median (MoM) after adjustment for variables relating to maternal characteristics and medical history that affect the measurements. Multivariable logistic regression analysis was used to determine if measuring UtA-PI improved the prediction of adverse perinatal outcome provided by screening with maternal characteristics, medical history and obstetric factors. The detection rate (DR) and false-positive rate (FPR) of screening by UtA-PI were estimated for stillbirth, Cesarean section for fetal distress, umbilical arterial cord blood pH ≤ 7.0 or umbilical venous cord blood pH ≤ 7.1 and 5-min Apgar score < 7.

RESULTS

The incidence of adverse perinatal outcome was higher in small-for-gestational-age (SGA) fetuses than in non-SGA fetuses, but the majority of cases with each adverse outcome were in the non-SGA group, including about 70% of stillbirths and more than 80% with Cesarean section for fetal distress, low cord blood pH and low Apgar score. The performance of UtA-PI > 95(th) percentile in screening for each adverse outcome was poor with DR of 6-16% and a FPR of 5-6%. The DR of adverse outcome when screening by high UtA-PI was greater in pregnancies complicated by SGA than in non-SGA pregnancies; 24% vs 13% for stillbirth, 15% vs 5% for Cesarean section for fetal distress, 30% vs 9% for low cord blood pH and 20% vs 3% for low 5-min Apgar score, respectively.

CONCLUSION

High UtA-PI at 30-34 weeks' gestation may be useful in the prediction of adverse perinatal outcome in pregnancies with a SGA fetus, however, in the absence of SGA, UtA-PI is a poor predictor of adverse outcome. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Contingent versus routine third-trimester screening for late fetal growth restriction

OBJECTIVE

To evaluate the use of third-trimester ultrasound screening for late fetal growth restriction (FGR) on a contingent basis, according to risk accrued in the second trimester, in an unselected population.

METHODS

Maternal characteristics, fetal biometry and second-trimester uterine artery (UtA) Doppler were included in logistic regression analysis to estimate risk for late FGR (birth weight < 3(rd) percentile, or 3(rd) -10(th) percentile plus abnormal cerebroplacental ratio or UtA Doppler, with delivery ≥ 34 weeks). Based on the second-trimester risk, strategies for performing contingent third-trimester ultrasound examinations in 10%, 25% or 50% of the cohort were tested against a strategy of routine ultrasound scanning in the entire population at 32 + 0 to 33 + 6 weeks.

RESULTS

Models were constructed based on 1393 patients and validated in 1303 patients, including 73 (5.2%) and 82 late FGR (6.3%) cases, respectively. At the second-trimester scan, the a-posteriori second-trimester risk (a-posteriori first-trimester risk (baseline a-priori risk and mean arterial blood pressure) combined with second-trimester abdominal circumference and UtA Doppler) yielded an area under the receiver-operating characteristics curve (AUC) of 0.81 (95% CI, 0.74-0.87) (detection rate (DR), 43.1% for a 10% false-positive rate (FPR)). The combination of a-posteriori second-trimester risk plus third-trimester estimated fetal weight (full model) yielded an AUC of 0.92 (95% CI, 0.88-0.96) (DR, 74% for a 10% FPR). Subjecting 10%, 25% or 50% of the study population to third-trimester ultrasound, based on a-posteriori second-trimester risk, gave AUCs of 0.81 (95% CI, 0.75-0.88), 0.84 (95% CI, 0.78-0.91) and 0.89 (95% CI, 0.84-0.94), respectively. Only the 50% contingent model proved statistically equivalent to performing routine third-trimester ultrasound scans (AUC, 0.92 (95% CI, 0.88-0.96), P = 0.11).

CONCLUSION

A strategy of selecting 50% of the study population to undergo third-trimester ultrasound examination, based on accrued risk in the second trimester, proved equivalent to routine third-trimester ultrasound scanning in predicting late FGR.

Prediction of small-for-gestational-age neonates: screening by biophysical and biochemical markers at 30-34 weeks

OBJECTIVE

To investigate the potential value of combined screening by maternal characteristics and medical history (maternal factors), estimated fetal weight (EFW), uterine artery pulsatility index (UtA-PI), mean arterial pressure (MAP) and serum levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) at 30-34 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE).

METHODS

This was a screening study in 9472 singleton pregnancies at 30-34 weeks' gestation, comprising 469 that delivered SGA neonates and 9003 cases unaffected by SGA, PE or gestational hypertension. Multivariable logistic regression analysis was used to determine if UtA-PI, MAP and serum PlGF or sFlt-1, individually or in combination, improved the prediction of SGA neonates provided from screening by maternal factors and EFW.

RESULTS

Compared to the normal group, mean log10 multiples of the median (MoM) values of UtA-PI, MAP and serum sFlt-1 were significantly higher and log10 MoM PlGF was lower in the SGA group. Multivariable logistic regression analysis demonstrated that in the prediction of SGA neonates with a birth weight < 5(th) percentile, delivering < 5 weeks and ≥ 5 weeks after assessment, there were significant independent contributions from maternal factors, EFW, UtA-PI, MAP, and serum PlGF and sFlt-1, but the best performance was provided by a combination of maternal factors, EFW, UtA-PI, MAP and serum PlGF, excluding sFlt-1. Combined screening predicted, at a 10% false-positive rate, 89%, 94%, 96% of SGA neonates delivering at 32-36 weeks' gestation with birth weight < 10(th) , < 5(th) and < 3(rd) percentiles, respectively; the respective detection rates of combined screening for SGA neonates delivering ≥ 37 weeks were 57%, 65% and 72%.

CONCLUSION

Combined screening by maternal factors and biophysical and biochemical markers at 30-34 weeks' gestation could identify a high proportion of pregnancies that will deliver SGA neonates.

Prediction of small-for-gestational-age neonates: screening by uterine artery Doppler and mean arterial pressure at 19-24 weeks

OBJECTIVE

To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 19-24 weeks' gestation, in combination with maternal characteristics and medical history and fetal biometry in the prediction of delivery of small-for-gestational-age (SGA) neonates in the absence of pre-eclampsia (PE) and to examine the potential value of such assessment in deciding whether the third-trimester scan should be performed at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 63 975 singleton pregnancies, including 3702 (5.8%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th) ) in the absence of PE. Multivariable logistic regression analysis was used to determine if screening by a combination of maternal factors, fetal head circumference (HC), abdominal circumference (AC), femur length (FL), UtA-PI and MAP had significant contribution in predicting SGA neonates. A model was developed to select gestational age for the third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

The detection rates (DRs) of combined screening by maternal factors, fetal biometry and UtA-PI at 19-24 weeks were 90%, 68% and 44% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The performance of screening was not improved by the addition of MAP. The DR of SGA < 5(th) delivering at 32-36 weeks improved from 68% to 90% with screening at 32 rather than at 19-24 weeks. Similarly, the DR of SGA < 5(th) delivering ≥ 37 weeks improved from 44% with screening at 19-24 weeks to 59% and 76% when screening at 32 and 36 weeks, respectively. In a hypothetical model, it was estimated that if the desired objective of prenatal screening is to predict about 80% of the cases of SGA < 5(th) , it would be necessary to select 17% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 38% to be reassessed at 36 weeks; 62% would not require a third-trimester scan.

CONCLUSION

Prenatal prediction of a high proportion of SGA neonates necessitates the undertaking of screening in the third trimester of pregnancy in addition to assessment in the second trimester, and the timing of such screening, at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.

Prediction of small-for-gestational-age neonates: screening by uterine artery Doppler and mean arterial pressure at 35-37 weeks

OBJECTIVE

To investigate the potential value of uterine artery (UtA) pulsatility index (PI) and mean arterial pressure (MAP) at 35-37 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE).

METHODS

This was a screening study in singleton pregnancies at 35-37 weeks, including 245 that delivered SGA neonates with birth weight < 5(th) percentile and 4876 cases unaffected by SGA, PE or gestational hypertension. Multivariable logistic regression analysis was used to determine if UtA-PI and MAP improved the prediction of SGA neonates provided by screening with maternal characteristics and medical history (maternal factors), and estimated fetal weight (EFW) from fetal head circumference, abdominal circumference and femur length.

RESULTS

Compared to the normal group, the median multiple of the median (MoM) values of UtA-PI and MAP were significantly higher in the SGA < 5(th) group. Combined screening by maternal factors, EFW Z-score, UtA-PI and MAP at 35-37 weeks predicted, at a 10% false-positive rate, 90%, 86% and 90% of SGA neonates with birth weight < 10(th) , < 5(th) and < 3(rd) percentiles, respectively, delivering < 2 weeks following assessment; the respective values for SGA delivering ≥ 37 weeks were 66%, 74% and 80%. Such performance was not significantly different from screening by maternal factors and EFW Z-score alone.

CONCLUSION

Addition of UtA-PI and MAP to combined testing by maternal factors and fetal biometry at 35-37 weeks does not improve the performance of screening for delivery of SGA neonates.