Prediction of small-for-gestational-age neonates: screening by fetal biometry at 30-34 weeks

How to enhance the applicability of a risk prediction model for term small-for-gestational-age neonates in clinical settings?

OBJECTIVE

To construct a simple term small-for-gestational-age (SGA) neonate prediction model that is clinically practical.

METHODS

This analysis was based on the Born in Guangzhou Cohort Study (BIGCS). Mothers who had a singleton pregnancy, delivered a term neonate, and had an ultrasonography within 30 + 0 to 32 + 6 weeks of gestation were included. Term SGA was defined with customized population percentiles. Prediction models were constructed with backward selection logistic regression in a four-step approach, where model 1 contained fetal biometrics only, models 2 and 3 included maternal features and a time factor (weeks between ultrasonography and delivery), respectively; and model 4 contained all features mentioned. The prediction performance of individual models was evaluated based on area under the curve (AUC) and a calibration test was performed.

RESULTS

The prevalence of SGA in the study population of 21 346 women was 11.5%. With a complete-case analysis approach, data of 19 954 women were used for model construction and validation. The AUC of the four models were 0.781, 0.793, 0.823, and 0.834, respectively, and all were well-calibrated. Model 3 consisted of fetal biometrics and corrected for time to delivery was chosen as the final model to build risk prediction graphs for clinical use.

CONCLUSION

A prediction model derived from fetal biometrics in early third trimester is satisfactory to predict SGA.

Diagnostic performance of 32 vs 36 weeks ultrasound in predicting late-onset fetal growth restriction and small-for-gestational-age neonates: a systematic review and meta-analysis

OBJECTIVE

Fetal growth restriction is an independent risk factor for fetal death and adverse neonatal outcomes. The main aim of this study was to investigate the diagnostic performance of 32 vs 36 weeks ultrasound of fetal biometry in detecting late-onset fetal growth restriction and predicting small-for-gestational-age neonates.

DATA SOURCES

A systematic search was performed to identify relevant studies published until June 2022, using the databases PubMed, Web of Science, and Scopus.

STUDY ELIGIBILITY CRITERIA

Cohort studies in low-risk or unselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation were used.

METHODS

The estimated fetal weight and abdominal circumference were assessed as index tests for the prediction of small for gestational age (birthweight of <10th percentile) and detecting fetal growth restriction (estimated fetal weight of <10th percentile and/or abdominal circumference of <10th percentile). The quality of the included studies was independently assessed by 2 reviewers using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. For the meta-analysis, hierarchical summary area under the receiver operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models.

RESULTS

The analysis included 25 studies encompassing 73,981 low-risk pregnancies undergoing third-trimester ultrasound assessment for growth, of which 5380 neonates (7.3%) were small for gestational age at birth. The pooled sensitivities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in predicting small for gestational age were 36% (95% confidence interval, 27%-46%) and 37% (95% confidence interval, 19%-60%), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-56%) and 50% (95% confidence interval, 25%-74%), respectively, at 36 weeks ultrasound. The pooled specificities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in detecting small for gestational age were 93% (95% confidence interval, 91%-95%) and 95% (95% confidence interval, 85%-98%), respectively, at 32 weeks ultrasound and 93% (95% confidence interval, 91%-95%) and 97% (95% confidence interval, 85%-98%), respectively, at 36 weeks ultrasound. The observed diagnostic odds ratios for an estimated fetal weight of <10th percentile and an abdominal circumference of <10th percentile in detecting small for gestational age were 8.8 (95% confidence interval, 5.4-14.4) and 11.6 (95% confidence interval, 6.2-21.6), respectively, at 32 weeks ultrasound and 13.3 (95% confidence interval, 10.4-16.9) and 36.0 (95% confidence interval, 4.9-260.0), respectively, at 36 weeks ultrasound. The pooled sensitivity, specificity, and diagnostic odds ratio in predicting fetal growth restriction were 71% (95% confidence interval, 52%-85%), 90% (95% confidence interval, 79%-95%), and 25.8 (95% confidence interval, 14.5-45.8), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-55%), 94% (95% confidence interval, 93%-96%), and 16.9 (95% confidence interval, 10.8-26.6), respectively, at 36 weeks ultrasound. Abdominal circumference of <10th percentile seemed to have comparable sensitivity to estimated fetal weight of <10th percentile in predicting small-for-gestational-age neonates.

CONCLUSION

An ultrasound assessment of the fetal biometry at 36 weeks of gestation seemed to have better predictive accuracy for small-for-gestational-age neonates than an ultrasound assessment at 32 weeks of gestation. However, an opposite trend was noted when the outcome was fetal growth restriction. Fetal abdominal circumference had a similar predictive accuracy to that of estimated fetal weight in detecting small-for-gestational-age neonates.

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.

Personalized Model to Predict Small for Gestational Age at Delivery Using Fetal Biometrics, Maternal Characteristics, and Pregnancy Biomarkers: A Retrospective Cohort Study of Births Assisted at a Spanish Hospital

Small for gestational age (SGA) is defined as a newborn with a birth weight for gestational age < 10th percentile. Routine third-trimester ultrasound screening for fetal growth assessment has detection rates (DR) from 50 to 80%. For this reason, the addition of other markers is being studied, such as maternal characteristics, biochemical values, and biophysical models, in order to create personalized combinations that can increase the predictive capacity of the ultrasound. With this purpose, this retrospective cohort study of 12,912 cases aims to compare the potential value of third-trimester screening, based on estimated weight percentile (EPW), by universal ultrasound at 35−37 weeks of gestation, with a combined model integrating maternal characteristics and biochemical markers (PAPP-A and β-HCG) for the prediction of SGA newborns. We observed that DR improved from 58.9% with the EW alone to 63.5% with the predictive model. Moreover, the AUC for the multivariate model was 0.882 (0.873−0.891 95% C.I.), showing a statistically significant difference with EPW alone (AUC 0.864 (95% C.I.: 0.854−0.873)). Although the improvements were modest, contingent detection models appear to be more sensitive than third-trimester ultrasound alone at predicting SGA at delivery.

Prediction of late-onset fetal growth restriction using a combined first- and second-trimester screening model

BACKGROUND

Prediction models for early fetal growth restriction (FGR) have been exhibited in many researches. However, prediction models for late FGR are limited. Late-onset FGR is easy to miss clinically because of its insidious onset. This study aimed to develop a simple combined first- and second-trimester prediction model for screening late-onset FGR in fetuses.

METHODS

This retrospective study included 2746 women who had singleton pregnancies and received routine ultrasound scans as training dataset. Late FGR is that diagnosed >32 weeks. Multivariate logistic regression was used to develop a prediction model.

RESULTS

One hundred and twenty-nine fetuses were identified as late-onset FGR. The significant predictors for late-onset FGR were maternal height, weight, and medical history; the first-trimester mean arterial pressure, the second-trimester head circumference/ abdominal circumference ratio; and the second-trimester estimated fetal weight. This model achieved a detection rate (DR........) of 51.6% for late-onset FGR at a 10% false positive rate (FPR) (area under the curve (AUC): 0.80, 95%CI 0.76-0.84).

CONCLUSIONS

A multivariate model combining first- and second-trimester default tests can detect 51.6% of cases of late-onset FGR at a 10% FPR. Further studies with more screening markers are needed to improve the detection rate.

The risk of recurrent small-for-gestational-age infants at term is dependent on the number of previously affected births

BACKGROUND

Small-for-gestational-age infants are at a substantially increased risk of perinatal complications, but the risk of recurrent small-for-gestational-age is not well known, particularly because there are many demographic and obstetrical factors that interact and modify this risk. We investigated the relationship between previous small-for-gestational-age births and the risk of recurrence at term in a large Australian cohort.

OBJECTIVE

We aimed to identify key demographic and obstetrical variables that influence the risk of recurrence of a small-for-gestational-age infant at term. The primary outcome measure was the odds of recurrence of small-for-gestational-age in subsequent pregnancies up to a maximum of 4 consecutive term births.

STUDY DESIGN

This was a retrospective analysis of women who had more than 1 consecutive nonanomalous, singleton, term live births between July 1997 and September 2018 at the Mater Mother's Hospital in Brisbane, Australia. Women with multiple pregnancy, preterm birth, or major congenital malformations were excluded. Small-for-gestational-age was defined as birthweight at the <10th centile. We calculated the odds of recurrence depending on the number of previous small-for-gestational-age infants and if only the preceding infant was small-for-gestational-age. The study population was dichotomized into small-for-gestational-age and non-small-for-gestational-age for each consecutive pregnancy. Univariate analyses compared baseline demographic and obstetrical characteristics followed by logistic regression modeling to determine the odds of recurrence in the second, third, and fourth pregnancies.

RESULTS

The final study comprised 24,819 women. The proportion of women who had a small-for-gestational-age infant in their first pregnancy was 9.4%, whereas the proportion of women who had a small-for-gestational-age infant in their second, third, and fourth pregnancies after the birth of a previous small-for-gestational-age infant were 20.5% (479 of 2338), 24.6% (63 of 256), and 30.4% (14 of 46), respectively. Regardless of parity, the odds of recurrence increased if the preceding infant was small-for-gestational-age. The odds of recurrence increased markedly if there was more than 1 previous small-for-gestational-age infant. In women with 3 previous small-for-gestational-age infants, the adjusted odds of another small-for-gestational-age infant were 66.00 (95% confidence interval, 11.35-383.76). Maternal age, body mass index, ethnicity, and smoking were significant risk factors for recurrent small-for-gestational-age. However, maternal diabetes mellitus or hypertension, either in a previous or current pregnancy, did not influence the risk of recurrence.

CONCLUSION

The risk of recurrence in a subsequent pregnancy increased if there was a previous small-for-gestational-age birth. Women with consecutive small-for-gestational-age infants were at the highest risk of recurrence. Our results highlight that women with a previous small-for-gestational-age infant are at a substantial risk of another small infant and need to be counseled and monitored appropriately.

Placental MRI: Longitudinal relaxation time (T1) in appropriate and small for gestational age pregnancies

OBJECTIVE

The antenatal detection of small for gestational age (SGA) pregnancies is a challenge, which may be improved by placental MRI. The longitudinal relaxation time (T1) is a tissue constant related to tissue morphology and tissue oxygenation, thereby placental T1 may be related to placental function. The aim of this study is to investigate placental T1 in appropriate for gestational age (AGA) and SGA pregnancies.

METHODS

A total of 132 singleton pregnancies were retrieved from our MRI research database. MRI and ultrasound estimated fetal weight (EFW) was performed at gestational week 20.6-41.7 in a 1.5 T system. SGA was defined as BW ≤ -15% of the expected for gestational age (≤10th centile). A subgroup of SGA pregnancies underwent postnatal placental histological examination (PHE) and abnormal PHE was defined as vascular malperfusion. The placental T1 values were converted into Z-scores adjusted for gestational age at MRI. The predictive performance of placental T1 and EFW was compared by receiver operating curves (ROC).

RESULTS

In AGA pregnancies, placental T1 showed a negative linear correlation with gestational age (r = -0.36, p = 0.004) Placental T1 was significantly reduced in SGA pregnancies (mean Z-score = -0.34) when compared to AGA pregnancies, p = 0.03. Among SGA pregnancies placental T1 was not reduced in cases with abnormal PHE, p = 0.84. The predictive performance of EFW (AUC = 0.84, 95% CI, 0.77-0.91) was significantly stronger than placental T1 (AUC = 0.62, 95% CI, 0.52-0.72) (p = 0.002).

DISCUSSION

A low placental T1 relaxation time is associated with SGA at birth. However, the predictive performance of placental T1 is not as strong as EFW.

Nomogram of fetal right portal vein diameter at gestational age 30 to 35 weeks and prediction of small for gestational age at birth

AIM

To construct the nomogram of fetal right portal vein (RPV) diameter at 30 to 35 weeks' gestation in Thai pregnant population and the use of RPV measurement to predicting small for gestational age (SGA) fetus.

METHODS

A prospective, cross-sectional study of singleton pregnancies at antenatal visit between 30 and 35⁺⁶ weeks of gestation in single center, Bhumibol Adulyadej Hospital (BAH) was conducted from January to August 2020. Ultrasonography of fetal biometry and RPV diameter measurement were performed as well as immediate newborn birth weight measurement. The nomogram of fetal RPV was developed for standardization for Thai people.

RESULTS

A total of 219 singleton pregnant women were enrolled and ultrasonographic measurement of RPV and fetal biometry was obtained. Mean maternal age and gestational period were 29.4 years and 33.0 weeks, respectively. One third of participants were classified as obese. RPV diameter ranged from 1.85 to 6.07 mm and increased linearly with gestational age. The optimal threshold of RPV diameter for diagnosis SGA was less than 3.06 mm with area under ROC curve at a level of 0.613 (95%CI 0.496 to 0.731). Sensitivity and specificity were 38.46% and 83.94%, respectively. There was no fetal death or neonatal morbidity in the present study.

CONCLUSION

RPV diameter increases in size depending on gestational age. RPV diameter at 30 to 35⁺⁶ weeks gestation was a useful measurement for SGA prediction. RPV measurements greater than 3.06 mm strongly indicated normal fetal growth.

Routine third-trimester ultrasound for the detection of small-for-gestational age in low-risk pregnancies (ROTTUS study): randomized controlled trial

OBJECTIVE

To compare the proportion of small-for-gestational-age (SGA) infants detected by routine third-trimester ultrasound vs those detected by selective ultrasound based on serial symphysis-fundus height (SFH) measurements (standard care) in low-risk pregnancy.

METHODS

This was an open-label randomized controlled trial conducted at a hospital in Kenya between May 2018 and February 2020. Low-risk pregnant women were randomly allocated (ratio of 1:1) to routine ultrasound for fetal growth assessment between 36 + 0 and 37 + 6 weeks' gestation (intervention group) or to standard care, which involved a selective growth scan on clinical suspicion of fetal growth abnormality based on serial SFH measurements (control group). During ultrasound examination, fetal growth was assessed by measurement of the abdominal circumference (AC), and AC < 10^th centile was used to diagnose a SGA fetus. The main prespecified outcomes were the detection of neonatal SGA, defined as birth weight < 10^th centile, and of severe neonatal SGA, defined as birth weight < 3^rd centile. The predictive performance of routine third-trimester ultrasound and selective ultrasound based on serial SFH measurements was determined using receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Of 566 women assessed for eligibility, 508 (89.8%) were randomized, of whom 253 were allocated to the intervention group and 255 to the control group. Thirty-six babies in the intervention group and 26 in the control group had a birth weight < 10^th centile. The detection rate of SGA infants by routine third-trimester ultrasound vs that by standard care was 52.8% (19/36) vs 7.7% (2/26) (P < 0.001) and the specificity was 95.5% (191/200) and 97.9% (191/195), respectively (P = 0.08). The detection rate of severe SGA was 66.7% (12/18) by routine ultrasound vs 8.3% (1/12) by selective ultrasound based on SFH measurements (P < 0.001), with specificities of 91.7% (200/218) and 98.1% (205/209), respectively (P = 0.006). The area under the ROC curve of routine third-trimester ultrasound in prediction of SGA was significantly greater than that of selective ultrasound based on SFH measurements (0.92 (95% CI, 0.87-0.96) vs 0.68 (95% CI, 0.58-0.77); P < 0.001).

CONCLUSIONS

In low-risk pregnancy, routine ultrasound performed between 36 + 0 and 37 + 6 weeks is superior to selective ultrasound based on serial SFH measurements for the detection of true SGA, with high specificity. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Competing-risks model for prediction of small-for-gestational-age neonate from estimated fetal weight at 19-24 weeks' gestation

OBJECTIVE

To develop further a new competing-risks model for the prediction of a small-for-gestational-age (SGA) neonate, by including second-trimester ultrasonographic estimated fetal weight (EFW).

METHODS

This was a prospective observational study in 96 678 women with singleton pregnancy undergoing routine ultrasound examination at 19-24 weeks' gestation. All pregnancies had ultrasound biometry assessment, and EFW was calculated according to the Hadlock formula. We refitted in this large dataset a previously described competing-risks model for the joint distribution of gestational age (GA) at delivery and birth-weight Z-score, according to maternal demographic characteristics and medical history, to obtain the prior distribution. The continuous likelihood of the EFW was fitted conditionally to GA at delivery and birth-weight Z-score and modified the prior distribution, according to Bayes' theorem, to obtain individualized distributions for GA at delivery and birth-weight Z-score and therefore patient-specific risks for any cut-offs for GA at delivery and birth-weight Z-score. We assessed the discriminative ability of the model for predicting SGA with, without or independently of pre-eclampsia occurrence. A calibration study was carried out. Performance of screening was evaluated for SGA defined according to the Fetal Medicine Foundation birth-weight charts.

RESULTS

The distribution of EFW, conditional to both GA at delivery and birth-weight Z-score, was best described by a regression model. For earlier gestations, the association between EFW and birth weight was steeper. The prediction of SGA by maternal factors and EFW improved for increasing degree of prematurity and greater severity of smallness but not for coexistence of pre-eclampsia. Screening by maternal factors predicted 31%, 34% and 39% of SGA neonates with birth weight < 10^th percentile delivered at ≥ 37, < 37 and < 30 weeks' gestation, respectively, at a 10% false-positive rate, and, after addition of EFW, these rates increased to 38%, 43% and 59%, respectively; the respective rates for birth weight < 3^rd percentile were 43%, 50% and 64%. The addition of EFW improved the calibration of the model.

CONCLUSION

In the competing-risks model for prediction of SGA, the performance of screening by maternal characteristics and medical history is improved by the addition of second-trimester EFW. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Third trimester ultrasound estimated fetal weight for increasing prenatal prediction of small-for-gestational age newborns in low-risk pregnant women

AIM

The early detection of small-for-gestational age (SGA) fetuses and newborns is pivotal in the prevention of perinatal mortality.

OBJECTIVES

To compare the predictive capability of performing ultrasound-based estimated fetal weight (EFW) at 32 versus 36 weeks' gestation on the detection rate of SGA fetuses and SGA newborns at delivery, and to find a better cutoff level to consider a fetus at risk of being born small.

MATERIAL AND METHODS

Nine hundred fifteen low-risk pregnant women were assessed at both 32 and 36 weeks' gestation. EFW centile was calculated in both occasions. The rate of SGA fetuses was compared. SGA fetuses were considered when both abdominal circumference (AC) and EFW were below the 10th centile from a total of 488 delivered at our Hospital. Paired comparisons between ultrasound at 32 and 36 weeks' gestation were done to predict SGA at delivery. Percentages of SGA fetuses were compared by chi-squared test. ANOVA test was used for comparing centiles among groups. Receiver operating characteristic (ROC) curve was used to find the best cutoff ultrasound centile to predict SGA at delivery. Statistical significance was previously set at 95% level (p < .05).

RESULTS

Ultrasound-based EFW at 32 weeks showed 23 cases of SGA (2.5%) while at 36 weeks this rate increased up to 4% (37/915) (p < .000001). When comparing both outcomes, 2.8% of those catalogued as adequate-for-gestational age (AGA) at 32 weeks were cases of SGA at 36 weeks. In addition, 47.8% of those diagnosed as SGA were not confirmed at 36 weeks. Only 12.3% of SGA neonates were identified at 32 weeks' gestation ultrasound, while using the 36 weeks' gestation approach this rate increased up to 30.9%. So, only a low proportion of SGA neonates were SGA fetuses at any of these two gestational ages. However, the area under the curve (AUC) at 36 weeks was as high as 0.86. Being a matter of cutoff rather than a matter of choosing the correct variable, ROC analysis showed that the best cutoff for prediction having the best sensitivity (0.80) with the best specificity (0.77) was 28th centile of EFW. This represents 24.9% of the studied women (228/915).

CONCLUSIONS

In general, ultrasound at 36 weeks has better performance detecting SGA fetuses than ultrasound at 32 weeks and we suggest to definitively change from 32 to 36 weeks in order to increase the detection rate of SGA fetuses. Moreover, in order to detect those fetuses who will grow below the lower level of the normal range in the last month of pregnancy, we suggest that those with EFW below the 28th centile at 36 weeks should be rescanned later in pregnancy to identify prenatally as many cases as we can of SGA newborns.

How to define late fetal growth restriction

A fraction of third-trimester small fetuses does not achieve their endowed growth potential mainly due to placental insufficiency, usually not evident in terms of impaired umbilical artery Doppler, but severe enough to increase the risk of perinatal adverse outcomes and long-term complications. The identification of those fetuses at higher-risk helps to optimize their follow-up and to decrease the risk of intrauterine demise. Several parameters can help in the identification of those fetuses at higher risk, defined as fetal growth restricted (FGR) fetuses. Severe smallness and the cerebroplacental ratio are the most consistent parameters; regarding uterine artery Doppler, although some evidence in favour has been published, there is currently no consensus about its use. Thirty-two weeks of gestation is the accepted cut-off to define late FGR. The differentiation with early FGR is necessary as these two entities have different clinical maternal manifestations, and different associated short-term and long-term neonatal outcomes. The use of angiogenic factors is promising but more research is needed on this field.

Placental Magnetic Resonance Imaging: A Method to Evaluate Placental Function In Vivo

This article describes the use of placental magnetic resonance imaging (MRI) relaxation times in the in vivo assessment of placental function. It focuses on T2*-weighted placental MRI, the main area of the authors' research over the past decade. The rationale behind T2*-weighted placental MRI, the main findings reported in the literature, and directions for future research and clinical applications of this method are discussed. The article concludes that placental T2* relaxation time is an easily obtained and robust measurement, which can discriminate between normal and dysfunctional placenta. Placenta T2* is a promising tool for in vivo assessment of placental function.

Midtrimester Ultrasound Predictors of Small-for-Gestational-Age Neonates

OBJECTIVES

To determine whether a specific estimated fetal weight (EFW) or abdominal circumference (AC) measurement percentile at the 18-to 24-week ultrasound (US) examination is associated with a small-for-gestational-age (SGA) neonate.

METHODS

A retrospective case-control study was conducted including women with uncomplicated singleton gestations who delivered a term SGA neonate identified as having a birth weight (BW) below the 10th percentile on the Olsen growth curve and had an 18- to 24-week US examination in our database. The study period was October 2011 to January 2018. A similar number of control charts were requested randomly over the same time with BW in the 10th to 90th percentiles, all which had an 18-to 24-week US examination in our database. After all neonates meeting BW criteria were identified, a chart review was performed to specifically evaluate biometric parameters from the US at 18 to 24 weeks to determine a potential correlation with the EFW percentile and AC percentile. Pregnancy, neonatal outcomes, and maternal demographic characteristics were collected.

RESULTS

A total of 549 term neonates with a BW below the 10th percentile, and 593 control term neonates with BW in the of 10th to 90th percentiles were reviewed. Our analyses revealed that the AC and EFW percentiles were poor predictors of BW (<10th percentile; areas under the receiver operating characteristic curves, 0.68 and 0.69, respectively). A similar low ability of AC and EFW to predict BW below the 5th percentile was noted.

CONCLUSIONS

(1) No tipping point or cutoff for the EFW or AC percentile at the 18- to 24-week US examination was identified to predict a term SGA neonate. (2) These data are helpful when counseling women in midgestation about specific parameters, their importance, and the potential need for follow up imaging.

Diagnosing Small for Gestational Age during second trimester routine screening: Early sonographic clues

OBJECTIVE

Small for gestational age (SGA) is generally defined as birth weight being at or below the 10th percentile. Children with SGA have a higher risk for complications. There is a need for early predictors, as the accurate diagnosis rate is only 50%. In the current study, we aimed to evaluate diagnostic performance of ultrasound (US)/color Doppler ultrasound (CDUS) parameters (umbilical vein-UV, right portal vein-RPV diameter/flow rate, and portal sinus-PS diameter) examined at 20-22 gestational week as SGA diagnostic factors.

MATERIALS AND METHODS

93 pregnant included (32 SGA, 61 controls). All the US examinations were performed between 20 and 22 weeks of gestation. UV, RPV, and PS measurements were performed by using the same image acquired for abdominal circumference measurement. A fetus with as estimated fetal weight (EFW) below the 10th percentile was diagnosed as SGA and SGA at birth was defined as having a birth weight under the 10th percentile.

RESULTS

Pregnant women in the SGA group were significantly older (30 ± 4.8 vs. 26.6 ± 5.4 years, p < 0.01). Median UV diameter was significantly lower in SGA group (2.20 vs. 2.40 mm, p = 0.001). Median RPV diameter was significantly lower in SGA group (2 vs. 2.10 mm, p = 0.018). Median PS diameter was significantly lower in SGA group (2 vs. 20.10 mm, p = 0.008).

CONCLUSION

UV, RPV, and PS diameters can be earlier predictors for SGA diagnosis. Routinely evaluation of these parameters during second trimester screening can increase SGA diagnosis rates and serve for early diagnose.

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.

Prediction of large-for-gestational-age neonate by routine third-trimester ultrasound

OBJECTIVES

First, to evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a large-for-gestational-age (LGA) neonate born at ≥ 37 weeks' gestation. Second, to assess the additive value of fetal growth velocity between 32 and 36 weeks' gestation to the performance of EFW at 35 + 0 to 36 + 6 weeks' gestation for prediction of a LGA neonate. Third, to define the predictive performance for a LGA neonate of different EFW cut-offs on routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Fourth, to propose a two-stage strategy for identifying pregnancies with a LGA fetus that may benefit from iatrogenic delivery during the 38^th gestational week.

METHODS

This was a retrospective study. First, data from 21 989 singleton pregnancies that had undergone routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks were used to compare the predictive performance of EFW and AC for a LGA neonate with birth weight > 90^th and > 97^th percentiles born at ≥ 37 weeks' gestation. Second, data from 14 497 singleton pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation and had a previous scan at 30 + 0 to 34 + 6 weeks were used to determine, through multivariable logistic regression analysis, whether addition of growth velocity, defined as the difference in EFW Z-score or AC Z-score between the early and late third-trimester scans divided by the time interval between the scans, improved the performance of EFW at 35 + 0 to 36 + 6 weeks in the prediction of delivery of a LGA neonate at ≥ 37 weeks' gestation. Third, in the database of the 45 847 pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation, the screen-positive and detection rates for a LGA neonate born at ≥ 37 weeks' gestation and ≤ 10 days after the initial scan were calculated for different EFW percentile cut-offs between the 50^th and 90^th percentiles.

RESULTS

First, the areas under the receiver-operating characteristics curves (AUC) of screening for a LGA neonate were significantly higher using EFW Z-score than AC Z-score and at 35 + 0 to 36 + 6 than at 31 + 0 to 33 + 6 weeks' gestation (P < 0.001 for all). Second, the performance of screening for a LGA neonate achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks was not significantly improved by addition of EFW growth velocity or AC growth velocity. Third, in screening by EFW > 90^th percentile at 35 + 0 to 36 + 6 weeks' gestation, the predictive performance for a LGA neonate born at ≥ 37 weeks' gestation was modest (65% and 46% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 10%), but the performance was better for prediction of a LGA neonate born ≤ 10 days after the scan (84% and 71% for neonates with birth weight > 97^th and > 90^th percentiles, respectively, at a screen-positive rate of 11%). Fourth, screening by EFW > 70^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 91% and 82% of LGA neonates with birth weight > 97^th and > 90^th percentiles, respectively, born at ≥ 37 weeks' gestation, at a screen-positive rate of 32%, and the respective values of screening by EFW > 85^th percentile for prediction of a LGA neonate born ≤ 10 days after the scan were 88%, 81% and 15%. On the basis of these results, it was proposed that routine fetal biometry at 36 weeks' gestation is a screening rather than diagnostic test for fetal macrosomia and that EFW > 70^th percentile should be used to identify pregnancies in need of another scan at 38 weeks, at which those with EFW > 85^th percentile should be considered for iatrogenic delivery during the 38^th  week.

CONCLUSIONS

First, the predictive performance for a LGA neonate by routine ultrasonographic examination during the third trimester is higher if the scan is carried out at 36 than at 32 weeks, the method of screening is EFW than fetal AC, the outcome measure is birth weight > 97^th than > 90^th percentile and if delivery occurs within 10 days than at any stage after assessment. Second, prediction of a LGA neonate by EFW > 90^th percentile is modest and this study presents a two-stage strategy for maximizing the prenatal prediction of a LGA neonate. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Could masking gestational age estimation during scanning improve detection of small-for-gestational-age fetuses? A controlled pre-post evaluation

BACKGROUND

Antenatal detection of small-for-gestational-age fetuses improves outcomes and reduces perinatal mortality rates. However, ultrasonographic estimation of fetal weight is subject to several potential sources of error. One potential source of error is subconscious operator bias towards "normal" measurement values for gestational age (observer-expectancy bias).

OBJECTIVE

We aimed to determine whether the sensitivity of small-for-gestational-age detection is improved by removing real-time display of estimated gestational age during measurement of the abdominal circumference in the third trimester.

STUDY DESIGN

This retrospective evaluation (November 2014-May 2018 inclusive) included all singleton infants liveborn at ≥28 weeks gestation in a single United Kingdom obstetrics center. In the preintervention phase, real-time estimated gestational age was displayed to sonographers as they measured fetal abdominal circumference (the key determinant of estimated fetal weight with the use of the INTERGROWTH 21st fetal weight equation) in the third trimester. In the postintervention phase, real-time gestational age information was removed on selected ultrasound machines. Accuracy of birthweight percentile estimation was assessed before and after intervention, both in the full cohort comprising all eligible scans and in a subcohort that was scanned within 4 weeks of delivery. We assessed the accuracy of small-for-gestational-age detection using the sensitivity, positive likelihood ratio, and area under the receiver-operator curve.

RESULTS

Of the 18,342 eligible pregnancies, 9342 (51%) had a third-trimester growth scan. The sensitivity of ultrasonographic estimation of fetal weight for antenatal detection of small-for-gestational-age babies did not change significantly between the before and after intervention phases (31.5% confidence interval, 27.1-36.2 vs 31.7% confidence interval, 20.2-45.0). Although the sensitivity for small-for-gestational-age detection was higher in the subcohort that was scanned within 4 weeks of delivery than in the full cohort (P<.001), there was no significant difference between the before and after intervention phases (58% confidence interval, 50-66 vs 65% confidence interval, 43-84). With the use of an estimation of the abdominal circumference percentile rather than estimated fetal weight percentile significantly decreased the sensitivity for small-for-gestational-age detection in all groups (P<.01), but there was no difference between the before and after intervention phases.

CONCLUSION

Blinding operators to the estimated gestation of the fetus during abdominal circumference measurement does not significantly alter the antenatal detection rate of small-for-gestational-age babies. The observer-expectancy effect is therefore unlikely to be a significant contributor to the error that is associated with ultrasonographic estimation of fetal weight.

Routine assessment of cerebroplacental ratio at 35-37 weeks' gestation in the prediction of adverse perinatal outcome

BACKGROUND

Third-trimester studies in selected high-risk pregnancies have reported that low cerebroplacental ratio, due to high pulsatility index in the umbilical artery, and or decreased pulsatility index in the fetal middle cerebral artery, is associated with increased risk of adverse perinatal outcomes.

OBJECTIVE

To investigate the predictive performance of screening for adverse perinatal outcome by the cerebroplacental ratio measured routinely at 35-37 weeks' gestation.

STUDY DESIGN

This was a prospective observational study in 47,211 women with singleton pregnancies undergoing routine ultrasound examination at 35⁺⁶ to 37⁺⁶ weeks' gestation, including measurement of umbilical artery-pulsatility index and middle cerebral artery-pulsatility index. The measured umbilical artery-pulsatility index and middle cerebral artery-pulsatility index and their ratio were converted to multiples of the median after adjustment for gestational age. Multivariable logistic regression analysis was used to determine whether umbilical artery-pulsatility index, middle cerebral artery-pulsatility index, and cerebroplacental ratio improved the prediction of adverse perinatal outcome that was provided by maternal characteristics, medical history, and obstetric factors. The following outcome measures were considered: (1) adverse perinatal outcome consisting of stillbirth, neonatal death, or hypoxic-ischemic encephalopathy grades 2 and 3; (2) presence of surrogate markers of perinatal hypoxia consisting of umbilical arterial or venous cord blood pH ≤7 and ≤7.1, respectively, 5-minute Apgar score <7, or admission to the neonatal intensive care unit for >24 hours; (3) cesarean delivery for presumed fetal compromise in labor; and (4) neonatal birthweight less than the third percentile for gestational age.

RESULTS

First, the incidence of adverse perinatal outcome, presence of surrogate markers of perinatal hypoxia, and cesarean delivery for presumed fetal compromise in labor was greater in pregnancies with small for gestational age neonates with birthweight <10th percentile compared with appropriate for gestational age neonates; however, 80%-85% of these adverse events occurred in the appropriate for gestational age group. Second, low cerebroplacental ratio <10th percentile was associated with increased risk of adverse perinatal outcome, presence of surrogate markers of perinatal hypoxia, cesarean delivery for presumed fetal compromise in labor, and birth of neonates with birthweight less than third percentile. However, multivariable regression analysis demonstrated that the prediction of these adverse outcomes by maternal demographic characteristics and medical history was only marginally improved by the addition of cerebroplacental ratio. Third, the performance of low cerebroplacental ratio in the prediction of each adverse outcome was poor, with detection rates of 13%-26% and a false-positive rate of about 10%. Fourth, the detection rates of adverse outcomes were greater in small for gestational age than in appropriate for gestational age babies and in pregnancies delivering within 2 weeks rather than at any stage after assessment; however, such increase in detection rates was accompanied by an increase in the false-positive rate. Fifth, in appropriate for gestational age neonates, the predictive accuracy of cerebroplacental ratio was low, with positive and negative likelihood ratios ranging from 1.21 to 1.82, and 0.92 to 0.98, respectively; although the accuracy was better in small for gestational age neonates, this was also low with positive likelihood ratios of 1.31-2.26 and negative likelihood ratios of 0.69-0.92. Similar values were obtained in fetuses classified as small for gestational age and appropriate for gestational age according to the estimated fetal weight.

CONCLUSIONS

In pregnancies undergoing routine antenatal assessment at 35-37 weeks' gestation, measurement of cerebroplacental ratio provides poor prediction of adverse perinatal outcome in both small for gestational age and appropriate for gestational age fetuses.

Better prediction for FGR (fetal growth restriction) with the sFlt-1/PIGF ratio: A case-control study

The aim of this study was to check whether the sFlt-1/PIGF ratio, established as the biomarker for preeclampsia, reduces the false positive rate of late fetal growth restriction (FGR) detection by ultrasound biometry.This was a prospective case-control study, conducted at one regional maternity hospital in Romania. Study participants included singleton pregnancy women for whom the estimated fetal weight (EFW) at 28 to 35 weeks was < 10 percentiles and as controls, pregnant women with EFW >10 percentiles. All pregnancies were dated in the first trimester by crown-rump-length. We also recorded maternal characteristics, pregnancy and neonatal outcomes.The primary outcome measures were the relation between the sFlt-1/PIGF ratio and incidence of FGR. Secondary outcome was establishing a threshold for statistical significance of the marker and influence of other conditions (e.g., pre-eclampsia) on the accuracy of the marker in FGR prediction.Included in the study were 37 pregnant women and 37 controls.When we used ultrasound (US) biometry and maternal risk factors to estimate EFW <10 percentiles, the sensitivity was 44.4% with a specificity of 89% for an FPR (false positive result) of 10%. When we combined the US biometry and maternal risk factors with sFlt1/PIGF ratio, for a cut off of 38, the sensitivity was 84.21%, and the specificity was 84.31% for an FPR of 10%. The cut off value (36) did not change if we considered all cases of SGA, including those with associated preeclampsia or if we considered only FGR cases without associated preeclampsia.When associated with maternal factors and US biometry, the sFlt1/PIGF ratio enhanced the sensitivity for detecting late FGR.

Routine ultrasound at 32 vs 36 weeks' gestation: prediction of small-for-gestational-age neonates

OBJECTIVE

To evaluate and compare the performance of routine ultrasonographic estimated fetal weight (EFW) and fetal abdominal circumference (AC) at 31 + 0 to 33 + 6 and 35 + 0 to 36 + 6 weeks' gestation in the prediction of a small-for-gestational-age (SGA) neonate.

METHODS

This was a prospective study of 21 989 singleton pregnancies undergoing routine ultrasound examination at 31 + 0 to 33 + 6 weeks' gestation and 45 847 undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. In each case, the estimated fetal weight (EFW) from measurements of fetal head circumference, AC and femur length was calculated using the Hadlock formula and expressed as a percentile according to The Fetal Medicine Foundation fetal and neonatal population weight charts. The same charts were used for defining a SGA neonate with birth weight < 10^th and < 3^rd percentiles. For each gestational-age window, the screen-positive and detection rates, at different EFW percentile cut-offs between the 10^th and 50^th percentiles, were calculated for prediction of delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment. The areas under the receiver-operating characteristics curves (AUC) in screening for a SGA neonate by EFW and AC at 31 + 0 to 33 + 6 and at 35 + 0 to 36 + 6 weeks' gestation were compared.

RESULTS

First, the AUCs in screening by EFW for a SGA neonate with birth weight < 10^th and < 3^rd percentiles delivered within 2 weeks and at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation were significantly higher than those at 31 + 0 to 33 + 6 weeks (P < 0.001). Second, at both 35 + 0 to 36 + 6 and 31 + 0 to 33 + 6 weeks' gestation, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born at any stage after screening was significantly higher using EFW Z-score than AC Z-score. Similarly, at 35 + 0 to 36 + 6 weeks, but not at 31 + 0 to 33 + 6 weeks, the predictive performance for a SGA neonate with birth weight < 10^th and < 3^rd percentiles born within 2 weeks after screening was significantly higher using EFW Z-score than AC Z-score. Third, screening by EFW < 10^th percentile at 35 + 0 to 36 + 6 weeks' gestation predicted 70% and 84% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 46% and 65%. Fourth, prediction of > 85% of SGA neonates with birth weight < 10^th percentile born at any stage after screening at 35 + 0 to 36 + 6 weeks' gestation requires use of EFW < 40^th percentile. Screening at this percentile cut-off predicted 95% and 99% of neonates with birth weight < 10^th and < 3^rd percentiles, respectively, born within 2 weeks after assessment, and the respective values for a neonate born at any stage after assessment were 87% and 94%.

CONCLUSIONS

The predictive performance for a SGA neonate of routine ultrasonographic examination during the third trimester is higher if, first, the scan is carried out at 35 + 0 to 36 + 6 weeks' gestation than at 31 + 0 to 33 + 6 weeks, second, the method of screening is EFW than fetal AC, third, the outcome measure is birth weight < 3^rd than < 10^th percentile, and, fourth, if delivery occurs within 2 weeks than at any stage after assessment. Prediction of a SGA neonate by EFW < 10^th percentile is modest and prediction of > 85% of cases at 35 + 0 to 36 + 6 weeks' gestation necessitates use of EFW < 40^th percentile. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnostic performance of third-trimester ultrasound for the prediction of late-onset fetal growth restriction: a systematic review and meta-analysis

OBJECTIVE

The objective of the study was to establish the diagnostic performance of ultrasound screening for predicting late smallness for gestational age and/or fetal growth restriction.

DATA SOURCES

A systematic search was performed to identify relevant studies published since 2007 in English, Spanish, French, Italian, or German, using the databases PubMed, ISI Web of Science, and SCOPUS.

STUDY ELIGIBILITY CRITERIA

We used rrospective and retrospective cohort studies in low-risk or nonselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation.

STUDY APPRAISAL AND SYNTHESIS METHODS

The estimated fetal weight and fetal abdominal circumference were assessed as index tests for the prediction of birthweight <10th (i.e. smallness for gestational age), less than the fifth, and less than the third centile and fetal growth restriction (estimated fetal weight less than the third or estimated fetal weight <10th plus Doppler signs). Quality of the included studies was independently assessed by 2 reviewers, using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. For the meta-analysis, hierarchical summary receiver-operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models. The sensitivity of the abdominal circumference <10th centile and estimated fetal weight <10th centile for a fixed 10% false-positive rate was derived from the corresponding hierarchical summary receiver-operating characteristic curves. Heterogeneity between studies was visually assessed using Galbraith plots, and publication bias was assessed by funnel plots and quantified by Deeks' method.

RESULTS

A total of 21 studies were included. Observed pooled sensitivities of abdominal circumference and estimated fetal weight <10th centile for birthweight <10th centile were 35% (95% confidence interval, 20-52%) and 38% (95% confidence interval, 31-46%), respectively. Observed pooled specificities were 97% (95% confidence interval, 95-98%) and 95% (95% confidence interval, 93-97%), respectively. Modeled sensitivities of abdominal circumference and estimated fetal weight <10th centile for 10% false-positive rate were 78% (95% confidence interval, 61-95%) and 54% (95% confidence interval, 46-52%), respectively. The sensitivity of estimated fetal weight <10th centile was better when aimed to fetal growth restriction than to smallness for gestational age. Meta-regression analysis showed a significant increase in sensitivity when ultrasound evaluation was performed later in pregnancy (P = .001).

CONCLUSION

Third-trimester abdominal circumference and estimated fetal weight perform similar in predicting smallness for gestational age. However, for a fixed 10% false-positive rate extrapolated sensitivity is higher for abdominal circumference. There is evidence of better performance when the scan is performed near term and when fetal growth restriction is the targeted condition.

Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 32 and 36 weeks

OBJECTIVE

To assess the additive value of fetal growth velocity between 32 and 36 weeks' gestation to the performance of ultrasonographic estimated fetal weight (EFW) at 35 + 0 to 36 + 6 weeks' gestation for prediction of delivery of a small-for-gestational-age (SGA) neonate and adverse perinatal outcome.

METHODS

This was a prospective study of 14 497 singleton pregnancies undergoing routine ultrasound examination at 30 + 0 to 34 + 6 and at 35 + 0 to 36 + 6 weeks' gestation. Multivariable logistic regression analysis was used to determine whether addition of growth velocity, defined as the difference in EFW Z-score or abdominal circumference (AC) Z-score between the early and late third-trimester scans divided by the time interval between the scans, improved the performance of EFW Z-score at 35 + 0 to 36 + 6 weeks in the prediction of, first, delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment and, second, a composite of adverse perinatal outcome, defined as stillbirth, neonatal death or admission to the neonatal unit for ≥ 48 h.

RESULTS

Multivariable logistic regression analysis demonstrated that significant contributors to the prediction of a SGA neonate were EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation, fetal growth velocity, by either AC Z-score or EFW Z-score, and maternal risk factors. The area under the receiver-operating characteristics curve (AUC) and detection rate (DR), at a 10% screen-positive rate, for prediction of a SGA neonate < 10^th percentile born within 2 weeks after assessment achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks (AUC, 0.938 (95% CI, 0.928-0.947); DR, 80.7% (95% CI, 77.6-83.9%)) were not significantly improved by addition of EFW growth velocity and maternal risk factors (AUC, 0.941 (95% CI, 0.932-0.950); P = 0.061; DR, 82.5% (95% CI, 79.4-85.3%)). Similar results were obtained when growth velocity was defined by AC rather than EFW. Similarly, there was no significant improvement in the AUC and DR, at a 10% screen-positive rate, for prediction of a SGA neonate < 10^th percentile born at any stage after assessment or a SGA neonate < 3^rd percentile born within 2 weeks or at any stage after assessment, achieved by EFW Z-score at 35 + 0 to 36 + 6 weeks by addition of maternal factors and either EFW growth velocity or AC growth velocity. Multivariable logistic regression analysis demonstrated that the only significant contributor to adverse perinatal outcome was maternal risk factors. Multivariable logistic regression analysis in the group with EFW < 10^th percentile demonstrated that significant contribution to prediction of delivery of a neonate with birth weight < 10^th and < 3^rd percentiles and adverse perinatal outcome was provided by EFW Z-score at 35 + 0 to 36 + 6 weeks, but not by AC growth velocity < 1^st decile.

CONCLUSION

The predictive performance of EFW at 35 + 0 to 36 + 6 weeks' gestation for delivery of a SGA neonate and adverse perinatal outcome is not improved by addition of estimated growth velocity between 32 and 36 weeks' gestation. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of small for gestational age neonates: screening by maternal factors, fetal biometry, and biomarkers at 35-37 weeks' gestation

BACKGROUND

Small for gestational age (SGA) neonates are at increased risk for perinatal mortality and morbidity; however, the risks can be substantially reduced if the condition is identified prenatally, because in such cases close monitoring and appropriate timing of delivery and prompt neonatal care can be undertaken. The traditional approach of identifying pregnancies with SGA fetuses is maternal abdominal palpation and serial measurements of symphysial-fundal height, but the detection rate of this approach is less than 30%. A higher performance of screening for SGA is achieved by sonographic fetal biometry during the third trimester; screening at 30-34 weeks' gestation identifies about 80% of SGA neonates delivering preterm but only 50% of those delivering at term, at a screen-positive rate of 10%. There is some evidence that routine ultrasound examination at 36 weeks' gestation is more effective than that at 32 weeks in predicting birth of SGA neonates.

OBJECTIVE

To investigate the potential value of maternal characteristics and medical history, sonographically estimated fetal weight (EFW) and biomarkers of impaired placentation at 35⁺⁰- 36⁺⁶ weeks' gestation in the prediction of delivery of SGA neonates.

MATERIALS AND METHODS

A dataset of 19,209 singleton pregnancies undergoing screening at 35⁺⁰-36⁺⁶ weeks' gestation was divided into a training set and a validation set. The training dataset was used to develop models from multivariable logistic regression analysis to determine whether the addition of uterine artery pulsatility index (UtA-PI), umbilical artery PI (UA-PI), fetal middle cerebral artery PI (MCA-PI), maternal serum placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFLT) would improve the performance of maternal factors and EFW in the prediction of delivery of SGA neonates. The models were then tested in the validation dataset to assess performance of screening.

RESULTS

First, in the training dataset, in the SGA group, compared to those with birthweight in ≥10th percentile, the median multiple of the median (MoM) values of PlGF and MCA-PI were reduced, whereas UtA-PI, UA-PI, and sFLT were increased. Second, multivariable regression analysis demonstrated that in the prediction of SGA in <10th percentile there were significant contributions from maternal factors, EFW Z-score, UtA-PI MoM, MCA-PI MoM, and PlGF MoM. Third, in the validation dataset, prediction of 90% of SGA neonates delivering within 2 weeks of assessment was achieved by a screen-positive rate of 67% (95% confidence interval [CI], 64-70%) in screening by maternal factors, 23% (95% CI, 20-26%) by maternal factors, and EFW and 21% (95% CI, 19-24%) by the addition of biomarkers. Fourth, prediction of 90% of SGA neonates delivering at any stage after assessment was achieved by a screen-positive rate of 66% (95% CI, 65-67%) in screening by maternal factors, 32% (95% CI, 31-33%) by maternal factors and EFW and 30% (95% CI, 29-31%) by the addition of biomarkers.

CONCLUSION

The addition of biomarkers of impaired placentation only marginally improves the predictive performance for delivery of SGA neonates achieved by maternal factors and fetal biometry at 35⁺⁰-36⁺⁶ weeks' gestation.

Fetal Medicine Foundation reference ranges for umbilical artery and middle cerebral artery pulsatility index and cerebroplacental ratio

OBJECTIVES

To develop gestational age-based reference ranges for the pulsatility index in the umbilical artery (UA-PI) and fetal middle cerebral artery (MCA-PI) and the cerebroplacental ratio (MCA-PI/UA-PI), and to examine the maternal characteristics and medical history that affect these measurements.

METHODS

This was a cross-sectional study of 72 387 pregnancies undergoing routine ultrasound examination at 20 + 0 to 22 + 6 weeks' gestation (n = 3712), 31 + 0 to 33 + 6 weeks (n = 29 035), 35 + 0 to 36 + 6 weeks (n = 37 252) or 41 + 0 to 41 + 6 weeks (n = 2388). For the purpose of this study, we included data for only one of the second- or third-trimester visits. The inclusion criteria were singleton pregnancy, dating by fetal crown-rump length at 11 + 0 to 13 + 6 weeks' gestation, live birth of a morphologically normal neonate and ultrasonographic measurements by sonographers who had received the Fetal Medicine Foundation Certificate of Competence in Doppler ultrasound. Since the objectives of the study were to establish reference ranges, rather than normal ranges, and to examine factors from maternal characteristics and medical history that affect these measurements, we included all pregnancies having routine ultrasound examinations, irrespective of whether the mother had a pre-existing medical condition, such as diabetes mellitus, or a pregnancy complication, such as pre-eclampsia or suspected fetal growth restriction. Median and SD models were fitted between UA-PI, MCA-PI and CPR and gestational age. Assessment of goodness of fit of the models was by inspection of quantile-to-quantile (Q-Q) plots of Z-scores calculated using the mean and SD models. The distributions of MCA-PI, UA-PI and CPR Z-scores were examined in relation to maternal characteristics and medical history.

RESULTS

The relationship between the median and gestational age was linear for UA-PI and cubic for MCA-PI and CPR and the SD was log quadratic for all three. MCA-PI and CPR increased with gestational age from 20 weeks' gestation to reach a peak at around 32 and 34 weeks, respectively, and decreased thereafter, whereas UA-PI decreased linearly with gestational age from 20 to 42 weeks. Compared to the general population, significant deviations in multiples of the median values of UA-PI, MCA-PI and CPR were observed in subgroups of maternal age, body mass index, racial origin, method of conception and parity.

CONCLUSION

This study established new reference ranges for UA-PI, MCA-PI and CPR, according to gestational age, and reports maternal characteristics and medical history that affect these measurements. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prediction of small-for-gestational-age neonates at 35-37 weeks' gestation: contribution of maternal factors and growth velocity between 20 and 36 weeks

OBJECTIVES

To evaluate the performance of ultrasonographic estimated fetal weight (EFW) at 35 + 0 to 36 + 6 weeks' gestation in the prediction of delivery of a small-for-gestational-age (SGA) neonate and assess the additive value of, first, maternal risk factors and, second, fetal growth velocity between 20 and 36 weeks' gestation in improving such prediction.

METHODS

This was a prospective study of 44 043 singleton pregnancies undergoing routine ultrasound examination at 19 + 0 to 23 + 6 and at 35 + 0 to 36 + 6 weeks' gestation. Multivariable logistic regression analysis was used to determine whether addition of maternal risk factors and growth velocity, the latter defined as the difference in EFW Z-score or fetal abdominal circumference (AC) Z-score between the third- and second-trimester scans divided by the time interval between the scans, improved the performance of EFW Z-score at 35 + 0 to 36 + 6 weeks in the prediction of delivery of a SGA neonate with birth weight < 10^th and < 3^rd percentiles within 2 weeks and at any stage after assessment.

RESULTS

Screening by EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation predicted 63.4% (95% CI, 62.0-64.7%) of neonates with birth weight < 10^th percentile and 74.2% (95% CI, 72.2-76.1%) of neonates with birth weight < 3^rd percentile born at any stage after assessment, at a screen-positive rate of 10%. The respective values for SGA neonates born within 2 weeks after assessment were 76.8% (95% CI, 74.4-79.0%) and 81.3% (95% CI, 78.2-84.0%). For a desired 90% detection rate of SGA neonate delivered at any stage after assessment, the necessary screen-positive rate would be 33.7% for SGA < 10^th percentile and 24.4% for SGA < 3^rd percentile. Multivariable logistic regression analysis demonstrated that, in the prediction of a SGA neonate with birth weight < 10^th and < 3^rd percentiles, there was a significant contribution from EFW Z-score at 35 + 0 to 36 + 6 weeks' gestation, maternal risk factors and AC growth velocity, but not EFW growth velocity. However, the area under the receiver-operating characteristics curve for prediction of delivery of a SGA neonate by screening with maternal risk factors and EFW Z-score was not improved by addition of AC growth velocity.

CONCLUSION

Screening for SGA neonates by EFW at 35 + 0 to 36 + 6 weeks' gestation and use of the 10^th percentile as the cut-off predicts 63% of affected neonates. Prediction of 90% of SGA neonates necessitates classification of about 35% of the population as being screen positive. The predictive performance of EFW is not improved by addition of estimated growth velocity between the second and third trimesters of pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Is it possible to safely prevent late preterm and early term births?

Late preterm and early term birth is associated with adverse short- and long-term consequences, particularly for neurodevelopment. A clear reduction in these births can be achieved by avoidance of non-medically indicated births prior to 39 weeks gestation, as shown following the introduction of prohibitive policies in the USA. However, clinicians and policy-makers must always consider the potential for unintended adverse consequences of such action, such as a potential for an increase in term stillbirth. Finding the balance between optimising long-term neurological outcomes and avoiding rare but devastating term stillbirths is one of the challenges of modern maternity care. In this article we review the current evidence for whether this balance can be found, where early births can be safely prevented, and what remains to be addressed to optimise this balance safely.

Prediction of SGA at Birth by Using the Right Portal Vein Diameter Measurement at the 30-35-Week Scan

OBJECTIVE

This study sought to test the hypothesis that the measurement of the right portal vein (RPV) diameter on the transverse abdominal view at the 32-week ultrasound scan is small in fetuses with growth retardation and to validate the use of this measurement as a tool for detecting small for gestational age (SGA) at birth.

METHODS

This was a retrospective cohort study at a single centre. The study population comprised 326 consecutive pregnancies, including 29 SGA at delivery and 297 unaffected cases. Stored images of the transverse view of the abdomen, obtained at the routine third trimester scan, were used to assess the diameters of the umbilical vein, the portal sinus, and the RPV.

RESULTS

The portal sinus and RPV diameter were smaller compared with the reference group (P = 0.021 and P < 0.001, respectively). Using a 10th percentile cut-off, the detection rate for SGA at birth was 38% for the RPV diameter versus 45% for the estimated fetal weight. The false-positive rates were 9% versus 8%, respectively. Multiple regression analysis revealed that RPV below the 10th percentile remained an independent four-fold risk factor for SGA (odds ratio [OR] 5.05; 95% confidence interval [CI] 1.94-13.14). Further analysis revealed a higher prevalence of induction of labour for non-reassuring fetal well-being (P = 0.005), fetal acidemia (P = 0.028), and admission to a neonatal intensive care unit (NICU, P = 0.029) in the RPV ≤10th percentile group.

CONCLUSION

RPV below the 10th percentile could be a reliable third trimester ultrasound marker of a subnormal fetal environment. This study proposed a new and accessible approach for prediction of SGA.

Screening for pre-eclampsia at 35-37 weeks' gestation

OBJECTIVE

To examine the performance of screening for pre-eclampsia (PE) at 35-37 weeks' gestation by maternal factors and combinations 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).

METHODS

This was a prospective observational study in women with singleton pregnancy attending for an ultrasound scan at 35 + 0 to 36 + 6 weeks as part of routine pregnancy care. Bayes' theorem was used to combine the prior distribution of gestational age at delivery with PE, obtained from maternal characteristics and medical history, with various combinations of biomarker multiples of the median (MoM) values to derive the patient-specific risks of delivery with PE. The performance of such screening was estimated.

RESULTS

The study population of 13 350 pregnancies included 272 (2.0%) that subsequently developed PE. In pregnancies that developed PE, the MoM values of MAP, UtA-PI and sFlt-1 were increased and PlGF MoM was decreased. At a risk cut-off of 1 in 20, the proportion of the population stratified into high risk was about 10% of the total, and the proportion of cases of PE contained within this high-risk group was 28% with screening by maternal factors alone; the detection rate increased to 53% with the addition of MAP, 67% with the addition of MAP and PlGF and 70% with the addition of MAP, PlGF and sFlt-1. The performance of screening was not improved by the addition of UtA-PI. The performance of screening depended on the racial origin of the women; in screening by a combination of maternal factors, MAP, PlGF and sFlt-1 and use of the risk cut-off of 1 in 20, the detection rate and screen-positive rate were 66% and 9.5%, respectively, for Caucasian women and 88% and 18% for those of Afro-Caribbean racial origin.

CONCLUSION

Screening by maternal factors and biomarkers at 35-37 weeks' gestation can identify a high proportion of pregnancies that develop late PE. The performance of screening depends on the racial origin of the women. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prediction and prevention of small-for-gestational-age neonates: evidence from SPREE and ASPRE

OBJECTIVES

To examine the effect of first-trimester screening for pre-eclampsia (PE) on the prediction of delivering a small-for-gestational-age (SGA) neonate and the effect of prophylactic use of aspirin on the prevention of SGA.

METHODS

The data for this study were derived from two multicenter studies. In SPREE, we investigated the performance of screening for PE by a combination of maternal characteristics and biomarkers at 11-13 weeks' gestation. In ASPRE, women with a singleton pregnancy identified by combined screening as being at high risk for preterm PE (> 1 in 100) participated in a trial of aspirin (150 mg/day from 11-14 until 36 weeks' gestation) compared to placebo. In this study, we used the data from the ASPRE trial to estimate the effect of aspirin on the incidence of SGA with birth weight < 10^th , < 5^th and < 3^rd percentile for gestational age. We also used the data from SPREE to estimate the proportion of SGA in the pregnancies with a risk for preterm PE of > 1 in 100.

RESULTS

In SPREE, screening for preterm PE by a combination of maternal factors, mean arterial pressure, uterine artery pulsatility index and serum placental growth factor identified a high-risk group that contained about 46% of SGA neonates < 10^th percentile born at < 37 weeks' gestation (preterm) and 56% of those born at < 32 weeks (early); the overall screen-positive rate was 12.2% (2014 of 16 451 pregnancies). In the ASPRE trial, use of aspirin reduced the overall incidence of SGA < 10^th percentile by about 40% in babies born at < 37 weeks' gestation and by about 70% in babies born at < 32 weeks; in babies born at ≥ 37 weeks, aspirin did not have a significant effect on incidence of SGA. The aspirin-related decrease in incidence of SGA was mainly due to its incidence decreasing in pregnancies with PE, for which the decrease was about 70% in babies born at < 37 weeks' gestation and about 90% in babies born at < 32 weeks. On the basis of these results, it was estimated that first-trimester screening for preterm PE and use of aspirin in the high-risk group would potentially reduce the incidence of preterm and early SGA by about 20% and 40%, respectively.

CONCLUSION

First-trimester screening for PE by the combined test identifies a high proportion of cases of preterm SGA that can be prevented by the prophylactic use of aspirin. © 2018 Crown copyright. Ultrasound in Obstetrics & Gynecology © 2018 ISUOG.

Term small-for-gestational-age infants from low-risk women are at significantly greater risk of adverse neonatal outcomes

BACKGROUND

Small-for-gestational-age infants (birthweight <0th centile) are at increased risk of perinatal complications but are frequently not identified antenatally, particularly in low-risk women delivering at term (≥37 weeks gestation). This is compounded by the fact that late pregnancy ultrasound is not the norm in many jurisdictions for this cohort of women. We thus investigated the relationship between birthweight <10th centile and serious neonatal outcomes in low-risk women at term.

OBJECTIVE(S)

We aimed to determine whether there is a difference of obstetric and perinatal outcomes for small-for-gestational-age infants, subdivided into fifth to <10th centile and less than the fifth centile cohorts compared with an appropriate-for-gestational age (birthweight 10th-90th centile) group at term.

STUDY DESIGN

This was a retrospective analysis of data from the Mater Mother's Hospital in Brisbane, Australia, for women who delivered between January 2000 and December 2015. Women with multiple pregnancy, diabetes mellitus, hypertension, preterm birth, major congenital anomalies, and large for gestational age infants (>90th centile for gestational age) were excluded. Small-for-gestational-age infants were subdivided into 2 cohorts: infants with birthweights from the fifth to <10th centile and those less than the fifth centile. Serious composite neonatal morbidity was defined as any of the following: Apgar score ≤3 at 5 minutes, respiratory distress syndrome, acidosis, admission into the neonatal intensive care unit, stillbirth, or neonatal death. Univariate and multivariate analyses were performed using generalized estimating equations to compare obstetric and perinatal outcomes for small-for-gestational-age infants compared with appropriate-for-gestational age controls.

RESULTS

The final study comprised 95,900 infants. Five percent were between the fifth and <10th centiles for birthweight and 4.3% were less than the fifth centile. The rate of serious composite neonatal morbidity was 11.1% in the control group, 13.7% in the fifth and <10th centile, and 22.6% in the less than the fifth centile cohorts, respectively. Even after controlling for confounders, both the fifth to <10th centiles and less than the fifth centile cohorts were at significantly increased risk of serious composite neonatal morbidity compared with controls (odds ratio, 1.25, 95% confidence interval, 1.15-1.37, and odds ratio, 2.20, 95% confidence interval, 2.03-2.39, respectively). Infants with birthweights <10th centile were more likely to have severe acidosis at birth, 5 minute Apgar score ≤3 and to be admitted to the neonatal intensive care unit. The serious composite neonatal morbidity was higher in infants less than the fifth centile compared with those in the fifth to <10th centile cohort (odds ratio, 1.71, 95% confidence interval, 1.52-1.92). The odds of perinatal death (stillbirth and neonatal death) were significantly higher in both small-for-gestational age groups than controls. After stratification for gestational age at birth, the composite outcome remained significantly higher in both small-for-gestational-age cohorts and was highest in the less than the fifth centile group at 37+0 to 38+6 weeks (odds ratio, 3.32, 95% confidence interval, 2.87-3.85). The risk of perinatal death was highest for infants less than the fifth centile at 37+0 to 38+6 weeks (odds ratio, 5.50, 95% confidence interval, 2.33-12.98).

CONCLUSION

Small-for-gestational-age infants from term, low-risk pregnancies are at significantly increased risk of mortality and morbidity when compared with appropriate-for-gestational age infants. Although this risk is increased at all gestational ages in infants less than the fifth centile for birthweight, it is highest at early-term gestation. Our findings highlight that early-term birth does not necessarily improve outcomes and emphasize the importance of identifying this cohort of infants.

Utility of Doppler parameters at 36-42 weeks' gestation in the prediction of adverse perinatal outcomes in appropriate-for-gestational-age fetuses

Aim

To investigate the potential value of Doppler ultrasound and to assess cerebroplacental ratio (CPR) in the prediction of adverse perinatal outcome defined as Apgar score < 7 at 1 minute.

Material and methods

This was a retrospective cross-sectional study in selected pregnant women undergoing an ultrasound examination between 36 and 42 weeks of gestation. We measured estimated fetal weight (EFW), mean umbilical artery pulsatility index (UA PI), mean middle cerebral artery pulsatility index (MCA PI), CPR, and Apgar score in 1 minute. Multiples of medians (MoM) were calculated for MCA PI and UA PI.

Results

The study group consisted of 446 women, 236 were primipara and 210 were multipara. The average age was 29.6 years (range 16–46 years). The average week of delivery is 39.5 weeks of gestation (range 36–42). Mean MCA PI and UA PI were 1.3 (0.1–2.45) and 0.8 (0.39–1.66), respectively. The mean values were 1.03 (0.1–1.9) for MCA PI MoM and 1.04 (0.5–2.1) for UA PI MoM. Primiparas had lower values of MCA PI (1.27 vs. 1.34), MCA PI MoM (1.00 vs. 1.05), CPR (1.62 vs. 1.73), EFW (3479.53 g vs. 3579.25 g) and birth weight (3513.50 g vs. 3617.79 g). For CPR cut-off point of 1.08: sensitivity was (0.945), specificity 0.1, positive predictive values 0.979, negative predictive values 0.04 and accuracy 0.926. The ROC curves for CPR were: area under the curve was 0.52 at CI 95% (0.342–0.698), p = 0.8271.

Conclusion

Screening in pregnancies with appropriate-for-gestational-age fetuses at 36–42 weeks of gestation using Doppler parameters is not useful in the prediction of adverse perinatal outcomes like an Apgar score < 7 at 1 minute.

Diagnosis and surveillance of late-onset fetal growth restriction

By consensus, late fetal growth restriction is that diagnosed >32 weeks. This condition is mildly associated with a higher risk of perinatal hypoxic events and suboptimal neurodevelopment. Histologically, it is characterized by the presence of uteroplacental vascular lesions (especially infarcts), although the incidence of such lesions is lower than in preterm fetal growth restriction. Screening procedures for fetal growth restriction need to identify small babies and then differentiate between those who are healthy and those who are pathologically small. First- or second-trimester screening strategies provide detection rates for late smallness for gestational age <50% for 10% of false positives. Compared to clinically indicated ultrasonography in the third trimester, universal screening triples the detection rate of late smallness for gestational age. As opposed to early third-trimester ultrasound, scanning late in pregnancy (around 37 weeks) increases the detection rate for birthweight <3rd centile. Contrary to early fetal growth restriction, umbilical artery Doppler velocimetry alone does not provide good differentiation between late smallness for gestational age and fetal growth restriction. A combination of biometric parameters (with severe smallness usually defined as estimated fetal weight or abdominal circumference <3rd centile) with Doppler criteria of placental insufficiency (either in the maternal [uterine Doppler] or fetal [cerebroplacental ratio] compartments) offers a classification tool that correlates with the risk for adverse perinatal outcome. There is no evidence that induction of late fetal growth restriction at term improves perinatal outcomes nor is it a cost-effective strategy, and it may increase neonatal admission when performed <38 weeks.

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.

The Impact of Kidney Development on the Life Course: A Consensus Document for Action

Hypertension and chronic kidney disease (CKD) have a significant impact on global morbidity and mortality. The Low Birth Weight and Nephron Number Working Group has prepared a consensus document aimed to address the relatively neglected issue for the developmental programming of hypertension and CKD. It emerged from a workshop held on April 2, 2016, including eminent internationally recognized experts in the field of obstetrics, neonatology, and nephrology. Through multidisciplinary engagement, the goal of the workshop was to highlight the association between fetal and childhood development and an increased risk of adult diseases, focusing on hypertension and CKD, and to suggest possible practical solutions for the future. The recommendations for action of the consensus workshop are the results of combined clinical experience, shared research expertise, and a review of the literature. They highlight the need to act early to prevent CKD and other related noncommunicable diseases later in life by reducing low birth weight, small for gestational age, prematurity, and low nephron numbers at birth through coordinated interventions. Meeting the current unmet needs would help to define the most cost-effective strategies and to optimize interventions to limit or interrupt the developmental programming cycle of CKD later in life, especially in the poorest part of the world.

Computing the Z Score and Centiles for Cross-sectional Analysis: A Practical Approach

Although Z scores have been reported in the literature, one of the problems for the nonstatistician is understanding the systematic approach used to compute the predicted mean and standard deviation, components of the Z score equation, which may vary as the independent variable changes over time (eg, gestational age). This review focuses on a step-by-step analysis using linear, quadratic, and fractional polynomials to compute the mean and standard deviation as a function of a continuous independent variable. Once the mean and standard deviation are computed, the Z score and centile can be derived and Z score calculators created that enable investigators to implement the results in the laboratory and/or clinical setting.

Prediction of small-for-gestational-age neonate by third-trimester fetal biometry and impact of ultrasound-delivery interval

OBJECTIVES

To compare third-trimester ultrasound screening methods to predict small-for-gestational age (SGA), and to evaluate the impact of the ultrasound-delivery interval on screening performance.

METHODS

In this prospective study, data were collected from a multicenter singleton cohort study investigating the links between various exposures during pregnancy with birth outcome and later health in children. We included women, recruited in the first trimester, who had complete outcome data and had undergone third-trimester ultrasound examination. Demographic, clinical and biological variables were also collected from both parents. We compared prediction of delivery of a SGA neonate (birth weight < 10^th percentile) by the following methods: abdominal circumference (AC) Z-score based on Hadlock curves (Hadlock AC), on INTERGROWTH-21^st Project curves (Intergrowth AC) and on Salomon curves (Salomon AC); estimated fetal weight (EFW) Z-score based on Hadlock curves (Hadlock EFW) and on customized curves from Gardosi (Gardosi EFW); and fetal growth velocity based on change in AC between second and third trimesters (FGVAC). We also assessed the following ultrasound-delivery intervals: ≤ 4 weeks, ≤ 6 weeks and ≤ 10 weeks.

RESULTS

Third-trimester ultrasound was performed in 1805 patients with complete outcome data, of whom 158 (8.8%) delivered a SGA neonate. Ultrasound examination was at a median gestational age of 32 (interquartile range, 31-33) weeks. The ultrasound-delivery interval was ≤ 4 weeks in 17.2% of cases, ≤ 6 weeks in 48.1% of cases and ≤ 10 weeks in 97.3% of cases. Areas under the receiver-operating characteristics curve (AUC) were 0.772 for Salomon AC, 0.768 for Hadlock EFW, 0.766 for Hadlock AC, 0.765 for Intergrowth AC, 0.708 for Gardosi EFW and 0.674 for FGVAC (all P < 0.0001). The screening method with the highest AUC for an ultrasound-delivery interval ≤ 4 weeks was Salomon AC (AUC, 0.856), ≤ 6 weeks was Hadlock AC (AUC, 0.824) and ≤ 10 weeks was Salomon AC (AUC, 0.780). At a fixed 10% false-positive rate, the best detection rates were 60.0%, 54.1% and 42.1% for intervals ≤ 4, ≤ 6 and ≤ 10 weeks, respectively.

CONCLUSION

Third-trimester ultrasound measurements provide poor to moderate prediction of SGA. A shorter ultrasound-delivery interval provides better prediction than does a longer interval. Further studies are needed to test the effect of including maternal or biological characteristics in SGA screening. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Pregnancy in the liver transplant recipient

During gestation, the woman's body undergoes various changes, and the line between physiology and pathology is very thin even in healthy women. Today, many of the liver transplant recipients are young women, who at one point in their lives may consider the possibility of pregnancy. Clinicians have to counsel them about the time of conception, the risk of miscarriage, the deterioration of the mother's health status, and the risk of birth defects. This review, based on our 20 years of clinical experience and up-to-date literature, provides comprehensive guidelines on pregnancy management in liver transplant recipients. Pregnancy in liver transplant recipients is possible but never physiological. Proper management and pharmacotherapy lowers the incidence of complications and birth defects. Critical factors for perinatal success include stable graft function before pregnancy, proper preparation for pregnancy, and cautious observation during its course. Liver Transplantation 22 1408-1417 2016 AASLD.

Concentrations of Mineral in Amniotic Fluid and Their Relations to Selected Maternal and Fetal Parameters

The concentrations of various trace elements in amniotic fluid (AF) change over the course of pregnancy, with gestational age and fetus growth. The aim of the present study was to evaluate the concentrations of selected essential and toxic elements in AF and their relations to maternal and fetal parameters. The study was carried out in 39 pregnant women, aged 34.6 ± 4.7 years, between weeks 16 and 26 of gestation. Amniotic fluid samples were obtained during the standard procedure of amniocentesis in high-risk patients for chromosomal abnormalities. An inductively coupled plasma mass spectrometry (ICP-MS) technique was used to determine the levels of Al, As, Ba, Cd, Co, Cr, Cu, Mg, Mn, Ni, Sr, U, and V in AF. Body mass and blood pressure were measured in all the women. The basic parameters of fetal development were also assayed. It was found that the age of the mother, the gender of the fetus, and the week of the pregnancy may affect the concentrations of mineral in the amniotic fluid. Moreover, several significant correlations between the essential and toxic elements and maternal and fetal parameters were observed. In particular, negative and positive correlations between fetal parameters and magnesium and copper levels in AF, respectively, were seen. The present findings demonstrate the association between minerals in AF and fetal development.

Identifying late-onset fetal growth restriction by measuring circulating placental RNA in the maternal blood at 28 weeks' gestation

BACKGROUND

Late-onset fetal growth restriction (FGR) is often undetected prior to birth, which puts the fetus at increased risk of adverse perinatal outcomes including stillbirth.

OBJECTIVE

Measuring RNA circulating in the maternal blood may provide a noninvasive insight into placental function. We examined whether measuring RNA in the maternal blood at 26-30 weeks' gestation can identify pregnancies at risk of late-onset FGR. We focused on RNA highly expressed in placenta, which we termed "placental-specific genes."

STUDY DESIGN

This was a case-control study nested within a prospective cohort of 600 women recruited at 26-30 weeks' gestation. The circulating placental transcriptome in maternal blood was compared between women with late-onset FGR (<5th centile at >36+6 weeks) and gestation-matched well-grown controls (20-95th centile) using microarray (n = 12). TaqMan low-density arrays, reverse transcription-polymerase chain reaction (PCR), and digital PCR were used to validate the microarray findings (FGR n = 40, controls n = 80).

RESULTS

Forty women developed late-onset FGR (birthweight 2574 ± 338 g, 2nd centile) and were matched to 80 well-grown controls (birthweight 3415 ± 339 g, 53rd centile, P < .05). Operative delivery and neonatal admission were higher in the FGR cohort (45% vs 23%, P < .05). Messenger RNA coding 137 placental-specific genes was detected in the maternal blood and 37 were differentially expressed in late-onset FGR. Seven were significantly dysregulated with PCR validation (P < .05). Activating transcription factor-3 messenger RNA transcripts were the most promising single biomarker at 26-30 weeks: they were increased in fetuses destined to be born FGR at term (2.1-fold vs well grown at term, P < .001) and correlated with the severity of FGR. Combining biomarkers improved prediction of severe late-onset FGR (area under the curve, 0.88; 95% CI 0.80-0.97). A multimarker gene expression score had a sensitivity of 79%, a specificity of 88%, and a positive likelihood ratio of 6.2 for subsequent delivery of a baby <3rd centile at term.

CONCLUSION

A unique placental transcriptome is detectable in maternal blood at 26-30 weeks' gestation in pregnancies destined to develop late-onset FGR. Circulating placental RNA may therefore be a promising noninvasive test to identify pregnancies at risk of developing FGR at term.

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 biophysical and biochemical markers at 19-24 weeks

OBJECTIVE

To investigate the value of combined screening by maternal characteristics and medical history, fetal biometry and biophysical and biochemical markers at 19-24 weeks' gestation, for prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 7816 singleton pregnancies, including 389 (5.0%) 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 biometry, uterine artery pulsatility index (UtA-PI) and maternal serum concentrations of placental growth factor (PlGF) and α-fetoprotein (AFP) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Significant independent contributions to the prediction of SGA < 5(th) were provided by maternal factors, fetal biometry, UtA-PI and serum PlGF and AFP. The detection rate (DR) of such combined screening at 19-24 weeks was 100%, 78% and 42% for SGA < 5(th) delivering < 32, at 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. 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 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 44% to be reassessed at 36 weeks; 57% 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 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 maternal serum biochemical markers at 19-24 weeks

OBJECTIVE

To investigate the value of maternal serum concentrations of placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG) and α-fetoprotein (AFP) at 19-24 weeks' gestation, in combination with maternal factors and fetal biometry, in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE) and 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 9715 singleton pregnancies, including 481 (5.0%) 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, Z-scores of fetal head circumference, abdominal circumference and femur length, and log10 multiples of the median (MoM) values of PlGF, sFlt-1, PAPP-A, free β-hCG or AFP had a significant contribution to the prediction of SGA neonates. A model was developed in selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Compared to the normal group, the mean log10 MoM value of PlGF was lower, AFP was higher and sFlt-1, PAPP-A and free β-hCG were not significantly different in the SGA < 5(th) group that delivered < 37 weeks. The detection rate (DR) of combined screening by maternal factors, fetal biometry and serum PlGF and AFP at 19-24 weeks was 100%, 76% and 38% for SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. 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 11% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 46% to be reassessed at 36 weeks; 54% 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 maternal biochemical markers at 30-34 weeks

OBJECTIVE

To investigate the potential value of serum placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), pregnancy-associated plasma protein-A (PAPP-A), free β-human chorionic gonadotropin (β-hCG) and α-fetoprotein (AFP) 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 singleton pregnancies at 30-34 weeks' gestation, including 490 that delivered SGA neonates and 9360 cases that were unaffected by SGA, PE or gestational hypertension (normal outcome). Multivariable logistic regression analysis was used to determine if screening by serum PlGF, sFlt-1, PAPP-A, free β-hCG and AFP, individually or in combination, 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 mean log10 multiples of the median (MoM) values of PlGF and AFP were significantly lower and the mean log10 MoM values of sFlt-1 and free β-hCG were significantly higher in the SGA group with a birth weight < 5(th) percentile (SGA < 5(th)) delivering < 5 weeks following assessment. The best model for prediction of SGA was provided by a combination of maternal factors, EFW and serum PlGF. Such combined screening, predicted, at a 10% false-positive rate, 85%, 93% and 92% of SGA neonates delivering < 5 weeks following assessment with birth weight < 10(th), < 5(th) and < 3(rd) percentiles, respectively; the respective detection rates of combined screening for SGA neonates delivering ≥ 5 weeks following assessment were 57%, 64% and 71%.

CONCLUSION

Combined screening by maternal factors, EFW and serum PlGF at 30-34 weeks' gestation can identify a high proportion of pregnancies that subsequently deliver SGA neonates.

Prediction of small-for-gestational-age neonates: screening by fetal biometry at 19-24 weeks

OBJECTIVE

To investigate the value of fetal biometry at 19-24 weeks' gestation in the prediction of delivery of small-for-gestational-age (SGA) neonates, in the absence of pre-eclampsia (PE), and examine the potential value of such assessment in deciding whether the third-trimester scan should be at 32 and/or 36 weeks' gestation.

METHODS

This was a screening study in 88,187 singleton pregnancies, including 5003 (5.7%) that delivered SGA neonates with birth weight < 5(th) percentile (SGA < 5(th)). Multivariable logistic regression analysis was used to determine if screening by a combination of maternal characteristics and medical history and Z-scores of fetal head circumference (HC), abdominal circumference (AC) and femur length (FL) had significant contribution in predicting SGA neonates. A model was developed for selecting the gestational age for third-trimester assessment, at 32 and/or 36 weeks, based on the results of screening at 19-24 weeks.

RESULTS

Combined screening by maternal factors and fetal biometry at 19-24 weeks, predicted 76%, 58% and 44% of SGA < 5(th) delivering < 32, 32-36 and ≥ 37 weeks' gestation, respectively, at a false-positive rate (FPR) of 10%. The detection rate (DR) of SGA < 5(th) delivering at 32-36 weeks improved from 58% to 82% with screening at 32 weeks 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 61% and 76% with 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 28% of the population at the 19-24-week assessment to be reassessed at 32 weeks and 41% to be reassessed at 36 weeks; in 59% of pregnancies there would be no need for 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, either at 32 and/or 36 weeks, should be contingent on the results of the assessment at 19-24 weeks.