Ultrasound screening for fetal growth restriction at 36 vs 32 weeks' gestation: a randomized trial (ROUTE)

Comparison of a Two (32/38 Weeks) versus One (36 Weeks) Ultrasound Protocol for the Detection of Decreased Fetal Growth and Adverse Perinatal Outcome

Third-trimester ultrasound has low sensitivity to small for gestational age (SGA) and adverse perinatal outcomes (APOs). The objective of this study was to compare, in terms of cost-effectiveness, two routine third-trimester surveillance protocols for the detection of SGA and evaluate the added value of a Doppler study for the prediction of APO. This was a retrospective observational study of low-risk pregnancies that were followed by a two growth scans protocol (P2) at 32 and 38 weeks or by a single growth scan at 36 weeks (P1). Ultrasound scans included an estimated fetal weight (EFW) in all cases and a Doppler evaluation in most cases. A total of 1011 pregnancies were collected, 528 with the P2 protocol and 483 with the P1 protocol. While the two models presented no differences for the detection of SGA in terms of sensitivity (47.89% vs. 50% p = 0.85) or specificity (94.97 vs. 95.86% p = 0.63), routine performance of two growth scans (P2) led to a 35% cost increase. The accuracy of EFW for the detection of SGA showed a noteworthy improvement when reducing the interval to labor, and the only parameter with predictive capacity of APO was the cerebroplacental ratio at 38 weeks. In low-risk pregnancies, the higher costs of a two-scan growth surveillance protocol at the third trimester are not justified by an increase in diagnostic effectivity.

Diagnosis, Prevention, and Management of Fetal Growth Restriction (FGR)

Fetal growth restriction (FGR), or intrauterine growth restriction (IUGR), is still the second most common cause of perinatal mortality. The factors that contribute to fetal growth restriction can be categorized into three distinct groups: placental, fetal, and maternal. The prenatal application of various diagnostic methods can, in many cases, detect the deterioration of the fetal condition in time because the nature of the above disorder is thoroughly investigated by applying a combination of biophysical and biochemical methods, which determine the state of the embryo-placenta unit and assess the possible increased risk of perinatal failure outcome and potential for many later health problems. When considering the potential for therapeutic intervention, the key question is whether it can be utilized during pregnancy. Currently, there are no known treatment interventions that effectively enhance placental function and promote fetal weight development. Nevertheless, in cases with fetuses diagnosed with fetal growth restriction, immediate termination of pregnancy may have advantages not only in terms of minimizing perinatal mortality but primarily in terms of reducing long-term morbidity during childhood and maturity.

Respiratory morbidity among offspring misclassified as growth restricted

OBJECTIVE

An ultrasound-based diagnosis implies that some fetuses suspected to be growth-restricted (FGR) are discovered at birth to be appropriately grown (appropriate for gestational age [AGA] birth weight, between the 10th and 90th percentile). These fetuses may thus be exposed to unnecessary medical interventions, including early labor induction. In this study, we have evaluated the long-term respiratory health of offspring misclassified as FGR.

STUDY DESIGN

A population-based cohort analysis was conducted, including deliveries of AGA singletons between 1991 and 2021 at a tertiary referral hospital. Incidence of morbidity due to various respiratory conditions was compared between AGA offspring with prenatal diagnosis of FGR, and those without a false diagnosis of FGR. The Kaplan-Meier approach was used to estimate cumulative morbidity incidence. The stratified Cox proportional-hazards model was used to control for confounders.

RESULTS

A total of 324,620 deliveries of AGA newborns were included in the analyses; 3249 of them (1.0%) were misclassified prenatally as FGR. The FGR subgroup delivered at an earlier gestational age (36.7 vs. 39.1 weeks, p < .001) and had more than 25% higher incidence of respiratory-related morbidity during childhood (33.2% vs. 26.5%), specifically related to asthma and obstructive sleep apnea (p < .001 for all). A higher cumulative morbidity rate due to respiratory conditions was observed in the Kaplan-Meier survival curve (log-rank p value < .001). This association between FGR and respiratory morbidity was independent of preterm delivery, maternal age, cesarean delivery, and child's birth year (adjusted hazard ratio = 1.14, 95% confidence interval: 1.07-1.21, p < .001), using a Cox proportional hazards model.

CONCLUSION

AGA newborns misclassified as FGR, are at an increased risk for long-term respiratory morbidity during childhood and adolescence.

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.

Indicated vs universal third-trimester ultrasound examination in low-risk pregnancies: a pre-post-intervention study

BACKGROUND

In low-risk pregnancies, a third-trimester ultrasound examination is indicated if fundal height measurement and gestational age discrepancy are observed. Despite potential improvement in the detection of ultrasound abnormality, prior trials to date on universal third-trimester ultrasound examination in low-risk pregnancies, compared with indicated ultrasound examination, have not demonstrated improvement in neonatal or maternal adverse outcomes.

OBJECTIVE

The primary objective was to determine if universal third-trimester ultrasound examination in low-risk pregnancies could attenuate composite neonatal adverse outcomes. The secondary objectives were to compare changes in composite maternal adverse outcomes and detection of abnormalities of fetal growth (fetal growth restriction or large for gestational age) or amniotic fluid (oligohydramnios or polyhydramnios).

STUDY DESIGN

Our pre-post intervention study at 9 locations included low-risk pregnancies, those without indication for ultrasound examination in the third trimester. Compared with indicated ultrasound in the preimplementation period, in the postimplementation period, all patients were scheduled for ultrasound examination at 36.0-37.6 weeks. In both periods, clinicians intervened on the basis of abnormalities identified. Composite neonatal adverse outcomes included any of: Apgar score ≤5 at 5 minutes, cord pH <7.00, birth trauma (bone fracture or brachial plexus palsy), intubation for >24 hours, hypoxic-ischemic encephalopathy, seizure, sepsis (bacteremia proven with blood culture), meconium aspiration syndrome, intraventricular hemorrhage grade III or IV, periventricular leukomalacia, necrotizing enterocolitis, stillbirth after 36 weeks, or neonatal death within 28 days of birth. Composite maternal adverse outcomes included any of the following: chorioamnionitis, wound infection, estimated blood loss >1000 mL, blood transfusion, deep venous thrombus or pulmonary embolism, admission to intensive care unit, or death. Using Bayesian statistics, we calculated a sample size of 600 individuals in each arm to detect >75% probability of any reduction in primary outcome (80% power; 50% hypothesized risk reduction).

RESULTS

During the preintervention phase, 747 individuals were identified during the initial ultrasound examination, and among them, 568 (76.0%) met the inclusion criteria at 36.0-37.6 weeks; during the postintervention period, the corresponding numbers were 770 and 661 (85.8%). The rate of identified abnormalities of fetal growth or amniotic fluid increased from between the pre-post intervention period (7.1% vs 22.2%; P<.0001; number needed to diagnose, 7; 95% confidence interval, 5-9). The primary outcome occurred in 15 of 568 (2.6%) individuals in the preintervention and 12 of 661 (1.8%) in the postintervention group (83% probability of risk reduction; posterior relative risk, 0.69 [95% credible interval, 0.34-1.42]). The composite maternal adverse outcomes occurred in 8.6% in the preintervention and 6.5% in the postintervention group (90% probability of risk; posterior relative risk, 0.74 [95% credible interval, 0.49-1.15]). The number needed to treat to reduce composite neonatal adverse outcomes was 121 (95% confidence interval, 40-200). In addition, the number to reduce composite maternal adverse outcomes was 46 (95% confidence interval, 19-74), whereas the number to prevent cesarean delivery was 18 (95% confidence interval, 9-31).

CONCLUSION

Among low-risk pregnancies, compared with routine care with indicated ultrasound examination, implementation of a universal third-trimester ultrasound examination at 36.0-37.6 weeks attenuated composite neonatal and maternal adverse outcomes.

Routine third-trimester ultrasound assessment for intrauterine growth restriction

Intrauterine growth restriction significantly impacts perinatal outcomes. Undetected IUGR escalates the risk of adverse outcomes. Serial symphysis-fundal height measurement, a recommended strategy, is insufficient in detecting abnormal fetal growth. Routine third-trimester ultrasounds significantly improve detection rates compared with this approach, but direct high-quality evidence supporting enhanced perinatal outcomes from routine scanning is lacking. In assessing fetal growth, abdominal circumference alone performs comparably to estimated fetal weight. Hadlock formulas demonstrate accurate fetal weight estimation across diverse gestational ages and settings. When choosing growth charts, prescriptive standards (encompassing healthy pregnancies) should be prioritized over descriptive ones. Customized fetal standards may enhance antenatal IUGR detection, but conclusive high-quality evidence is elusive. Emerging observational data suggest that longitudinal fetal growth assessment could predict adverse outcomes better. However, direct randomized trial evidence supporting this remains insufficient.

Prenatal prediction of adverse outcome using different charts and definitions of fetal growth restriction

OBJECTIVE

Antenatal growth assessment using ultrasound aims to identify small fetuses that are at higher risk of perinatal morbidity and mortality. This study explored whether the association between suboptimal fetal growth and adverse perinatal outcome varies with different definitions of fetal growth restriction (FGR) and different weight charts/standards.

METHODS

This was a retrospective cohort study of 17 261 singleton non-anomalous pregnancies at ≥ 24 + 0 weeks' gestation that underwent routine ultrasound at a tertiary referral hospital. Estimated fetal weight (EFW) and Doppler indices were converted into percentiles using a reference standard (INTERGROWTH-21st (IG-21)) and various reference charts (Hadlock, Fetal Medicine Foundation (FMF) and Swedish). Test characteristics were assessed using the consensus definition, Society for Maternal-Fetal Medicine (SMFM) definition and Swedish criteria for FGR. Adverse perinatal outcome was defined as perinatal death, admission to the neonatal intensive care unit at term, 5-min Apgar score < 7 and therapeutic cooling for neonatal encephalopathy. The association between FGR according to each definition and adverse perinatal outcome was compared. Multivariate logistic regression analysis was used to test the strength of association between ultrasound parameters and adverse perinatal outcome. Ultrasound parameters were also tested for correlation.

RESULTS

IG-21, Hadlock and FMF fetal size references classified as growth-restricted 1.5%, 3.6% and 4.6% of fetuses, respectively, using the consensus definition and 2.9%, 8.8% and 10.6% of fetuses, respectively, using the SMFM definition. The sensitivity of the definition/chart combinations for adverse perinatal outcome varied from 4.4% (consensus definition with IG-21 charts) to 13.2% (SMFM definition with FMF charts). Specificity varied from 89.4% (SMFM definition with FMF charts) to 98.6% (consensus definition with IG-21 charts). The consensus definition and Swedish criteria showed the highest specificity, positive predictive value and positive likelihood ratio in detecting adverse outcome, irrespective of the reference chart/standard used. Conversely, the SMFM definition had the highest sensitivity across all investigated growth charts. Low EFW, abnormal mean uterine artery pulsatility index (UtA-PI) and abnormal cerebroplacental ratio were significantly associated with adverse perinatal outcome and there was a positive correlation between the covariates. Multivariate logistic regression showed that UtA-PI > 95th percentile and EFW < 5th percentile were the only parameters consistently associated with adverse outcome, irrespective of the definitions or fetal growth chart/standard used.

CONCLUSIONS

The apparent prevalence of FGR varies according to the definition and fetal size reference chart/standard used. Irrespective of the method of classification, the sensitivity for the identification of adverse perinatal outcome remains low. EFW, UtA-PI and fetal Doppler parameters are significant predictors of adverse perinatal outcome. As these indices are correlated with one other, a prediction algorithm is advocated to overcome the limitations of using these parameters in isolation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Validation of Fetal Medicine Foundation competing-risks model for small-for-gestational-age neonate in early third trimester

OBJECTIVE

To evaluate the new 36-week Fetal Medicine Foundation (FMF) competing-risks model for the prediction of small-for-gestational age (SGA) at an earlier gestation of 30 + 0 to 34 + 0 weeks.

METHODS

This was a retrospective multicenter cohort study of prospectively collected data on 3012 women with a singleton pregnancy undergoing ultrasound examination at 30 + 0 to 34 + 0 weeks' gestation as part of a universal screening program. We used the default FMF competing-risks model for prediction of SGA at 36 weeks' gestation combining maternal factors (age, obstetric and medical history, weight, height, smoking status, race, mode of conception), estimated fetal weight (EFW) and uterine artery pulsatility index (UtA-PI) to calculate risks for different cut-offs of birth-weight percentile and gestational age at delivery. We examined the accuracy of the model by means of discrimination and calibration.

RESULTS

The prediction of SGA < 3rd percentile improved with the addition of UtA-PI and with a shorter examination-to-delivery interval. For a 10% false-positive rate, maternal factors, EFW and UtA-PI predicted 88.0%, 74.4% and 72.8% of SGA < 3rd percentile delivered at < 37, < 40 and < 42 weeks' gestation, respectively. The respective values for SGA < 10th percentile were 86.1%, 69.3% and 66.2%. In terms of population stratification, if the biomarkers used are EFW and UtA-PI and the aim is to detect 90% of SGA < 10th percentile, then 10.8% of the population should be scanned within 2 weeks after the initial assessment, an additional 7.2% (total screen-positive rate (SPR), 18.0%) should be scanned within 2-4 weeks after the initial assessment and an additional 11.7% (total SPR, 29.7%) should be examined within 4-6 weeks after the initial assessment. The new model was well calibrated.

CONCLUSIONS

The 36-week FMF competing-risks model for SGA is also applicable and accurate at 30 + 0 to 34 + 0 weeks and provides effective risk stratification, especially for cases leading to delivery < 37 weeks of gestation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Management of fetuses with apparent normal growth and abnormal cerebroplacental ratio: A risk-based approach near term

INTRODUCTION

Cerebroplacental ratio (CPR) has been shown to be an independent predictor of adverse perinatal outcome at term and a marker of failure to reach the growth potential (FRGP) regardless of fetal size, being abnormal in compromised fetuses with birthweight above the 10th centile. The main aim of this study was to propose a risk-based approach for the management of pregnancies with normal estimated fetal weight (EFW) and abnormal CPR near term.

MATERIAL AND METHODS

This was a retrospective study of 943 pregnancies, that underwent an ultrasound evaluation of EFW and CPR at or beyond 34 weeks. CPR values were converted into multiples of the median (MoM) and EFW into centiles according to local references. Pregnancies were then divided into four groups: normal fetuses (defined as EFW ≥10th centile and CPR ≥0.6765 MoM), small for gestational age (EFW <10th centile and CPR ≥0.6765 MoM), fetal growth restriction (EFW <10th centile and CPR <0.6765 MoM), and fetuses with apparent normal growth (EFW ≥10th centile) and abnormal CPR (<0.6765 MoM), that present FRGP. Intrapartum fetal compromise (IFC) was defined as an abnormal intrapartum cardiotocogram or pH requiring cesarean delivery. Risk comparisons were performed among the four groups, based on the different frequencies of IFC. The risks of IFC were subsequently extrapolated into a gestational age scale, defining the optimal gestation to plan the birth for each of the four groups.

RESULTS

Fetal growth restriction was the group with the highest frequency of IFC followed by FRGP, small for gestational age, and normal groups. The "a priori" risks of the fetal growth restriction and normal groups were used to determine the limits of two scales. One defining the IFC risk and the other defining the appropriate gestational age for delivery. Extrapolation of the risk between both scales placed the optimal gestational age for delivery at 39 weeks of gestation in the case of FRGP and at 40 weeks in the case of small for gestational age.

CONCLUSIONS

Fetuses near term may be evaluated according to the CPR and EFW defining four groups that present a progressive risk of IFC. Fetuses in pregnancies complicated by FRGP are likely to benefit from being delivered at 39 weeks of gestation.

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.

Insufficient antenatal identification of fetal growth restriction leading to intrauterine fetal death: a regional population-based study in Japan

OBJECTIVE

Fetal growth restriction (FGR) is associated with perinatal adverse outcomes including intrauterine fetal death. Antenatally unidentified FGR has a higher risk of intrauterine fetal death than that identified antenatally. We, therefore, investigated the antenatal identification of FGR among intrauterine fetal deaths, and assessed the perinatal factors associated with the identification of FGR.

METHODS

This retrospective and population-based study reviewed all stillbirths in Shiga Prefecture, Japan, from 2007 to 2016 with exclusion criteria of multiple births, births at unidentified gestational weeks or < 22 gestational weeks, and lethal disorders. We analyzed cases of FGR, using the Japanese clinical definition: Z-score of estimated fetal weight for gestational age <-1.5 standard deviations (SD).

RESULTS

We identified 94 stillbirths with FGR among 429 stillbirths. Thirty-seven cases were antenatally identified during pregnancy management (39%). Dividing cases by a Z-score of -2.5 SD, 51 cases were classified as ≤-2.5 SD. Twenty-eight of the 51 cases (55%) with a Z-score <-2.5 SD were antenatally identified as having FGR, whereas 9 of the 43 cases (21%) with a Z-score ≥-2.5 SD were antenatally identified as having FGR (p = .002). Among cases with a Z-Score <-2.5 SD, 16 of 21 (76%) beyond 28 weeks' gestation and 12 of 30 (40%) before 28weeks' gestation were antenatally identified as having FGR (p = .023).

CONCLUSION

Fetal growth restriction leading to intrauterine fetal death in Japan was antenatally identified in less than half of cases. Antenatal identification of FGR was associated with the severity of growth restriction.

Fetal growth restriction and small for gestational age as predictors of neonatal morbidity: which growth nomogram to use?

BACKGROUND

Fetal growth nomograms were developed to screen for fetal growth restriction and guide clinical care to improve perinatal outcomes; however, existing literature remains inconclusive regarding which nomogram is the gold standard.

OBJECTIVE

This study aimed to compare the ability of 4 commonly used nomograms (Hadlock, International Fetal and Newborn Growth Consortium for the 21st Century, Eunice Kennedy Shriver National Institute of Child Health and Human Development-unified standard, and World Health Organization fetal growth charts) and 1 institution-specific reference to predict small for gestational age and poor neonatal outcomes.

STUDY DESIGN

This was a retrospective cohort study of all nonanomalous singleton pregnancies undergoing ultrasound at ≥20 weeks of gestation between 2013 and 2020 and delivering at a single academic center. Using random selection methods, the study sample was restricted to 1 pregnancy per patient and 1 ultrasound per pregnancy completed at ≥22 weeks of gestation. Fetal biometry data were used to calculate estimated fetal weight and percentiles according to the aforementioned 5 nomograms. Maternal and neonatal data were extracted from electronic medical records. Logistic regression was used to estimate the association between estimated fetal weight of <10th and <3rd percentiles compared with estimated fetal weight of 10th to 90th percentile as the reference group for small for gestational age and the neonatal composite outcomes (perinatal mortality, hypoxic-ischemic encephalopathy or seizures, respiratory morbidity, intraventricular hemorrhage, necrotizing enterocolitis, hyperbilirubinemia or hypoglycemia requiring neonatal intensive care unit admission, and retinopathy of prematurity). Receiver operating characteristic curve contrast estimation (primary analysis) and test characteristics were calculated for all nomograms and the prediction of small for gestational age and the neonatal composite outcomes. We restricted the sample to ultrasounds performed within 28 days of delivery; moreover, similar analyses were completed to assess the prediction of small for gestational age and neonatal composite outcomes.

RESULTS

Among 10,045 participants, the proportion of fetuses classified as <10th percentile varied across nomograms from 4.9% to 9.7%. Fetuses with an estimated fetal weight of <10th percentile had an increased risk of small for gestational age (odds ratio, 9.9 [95% confidence interval, 8.5-11.5] to 12.8 [95% confidence interval, 10.9-15.0]). In addition, the estimated fetal weight of <10th and <3rd percentile was associated with increased risk of the neonatal composite outcome (odds ratio, 2.4 [95% confidence interval, 2.0-2.8] to 3.5 [95% confidence interval, 2.9-4.3] and 5.7 [95% confidence interval, 4.5-7.2] to 8.8 [95% confidence interval, 6.6-11.8], respectively). The prediction of small for gestational age with an estimated fetal weight of <10th percentile had a positive likelihood ratio of 6.3 to 8.5 and an area under the curve of 0.62 to 0.67. Similarly, the prediction of the neonatal composite outcome with an estimated fetal weight of <10th percentile had a positive likelihood ratio of 2.1 to 3.1 and an area under the curve of 0.55 to 0.57. When analyses were restricted to ultrasound within 4 weeks of delivery, among fetuses with an estimated fetal weight of <10th percentile, the risk of small for gestational age increased across all nomograms (odds ratio, 16.7 [95% confidence interval, 12.6-22.3] to 25.1 [95% confidence interval, 17.0-37.0]), and prediction improved (positive likelihood ratio, 8.3-15.0; area under the curve, 0.69-0.75). Similarly, the risk of neonatal composite outcome increased (odds ratio, 3.2 [95% confidence interval, 2.4-4.2] to 5.2 [95% confidence interval, 3.8-7.2]), and prediction marginally improved (positive likelihood ratio, 2.4-4.1; area under the curve, 0.60-0.62). Importantly, the risk of both being small for gestational age and having the neonatal composite outcome further increased (odds ratio, 21.4 [95% confidence interval, 13.6-33.6] to 28.7 (95% confidence interval, 18.6-44.3]), and the prediction of concurrent small for gestational age and neonatal composite outcome greatly improved (positive likelihood ratio, 6.0-10.0; area under the curve, 0.80-0.83).

CONCLUSION

In this large cohort, Hadlock, recent fetal growth nomograms, and a local population-derived fetal growth reference performed comparably in the prediction of small for gestational age and neonatal composite outcomes.

Screening for small for gestational age infants in early vs late third-trimester ultrasonography: a randomized trial

BACKGROUND

Recent studies have demonstrated that a routine third-trimester ultrasound scan may improve the detection of small for gestational age infants when compared with clinically indicated ultrasound scans but with no reported reduction in severe perinatal morbidity. Establishing the optimal gestational age for the third-trimester examination necessitates evaluation of the ability to detect small for gestational age infants and to predict maternal and perinatal outcomes. Intrauterine growth restriction most often corresponds with small for gestational age infants associated with pathologic growth patterns.

OBJECTIVE

This study aimed to assess the performance of routine early ultrasound scans vs late ultrasound scans during the third trimester of pregnancy to identify small for gestational age infants and fetuses with intrauterine growth restriction.

STUDY DESIGN

This was an open-label, randomized, parallel trial conducted in Upper Normandy, France, from 2012 to 2015. The study eligibility criteria were heathy, nulliparous women older than 18 years with gestational age determined using the crown-rump length at the first trimester routine scan and with no fetal malformation or suspected small for gestational age fetus at the routine second trimester scan. Pregnant women were randomly assigned to a third-trimester scan group at 31 weeks gestational age ±6 days (early ultrasound scan) or at 35 weeks gestational age ±6 days (late ultrasound scan). The primary outcome of this trial was the ability of a third trimester scan to predict small for gestational age infants (customized birth weight <10th percentile) and intrauterine growth restriction (customized birth weight

RESULTS

Results from 1853 women assigned to the early ultrasound scan group and 1848 women assigned to the late ultrasound scan group were analyzed. The sensitivity was found to be higher in the late ultrasound scan group than in the early ultrasound scan group, both for identifying small for gestational age infants (27%; 22%-32% vs 17%; 13%-22%; P=.004) and intrauterine growth restriction (44%; 35%-54% vs 18%; 11%-27%; P<.001). There was little difference in the specificity between the late ultrasound scan and early ultrasound scan groups in identifying cases of small for gestational age (97%; 96%-98% and 98%; 97%-99%, respectively; P=.04) and intrauterine growth restriction (96%; 95%-97% and 97%; 96%;-97%, respectively; P=.24). Overall, the maternal and neonatal outcomes were comparable between the early ultrasound scan and late ultrasound scan groups with the exception of additional (at least 1) ultrasound scans performed (25% in the early ultrasound scan group vs 19% in the late ultrasound scan group; P<.001). Rates of perinatal death (0.4% vs 0.8%; P=.12) and adverse perinatal outcomes (1.8% vs 2.7%; P=.08) were comparable between the early ultrasound scan and late ultrasound scan assigned groups, and the overall sensitivity to detect small for gestational age infants and intrauterine growth restriction, including in the last ultrasound scan performed before delivery, were also similar (30%; 25%-36% vs 26%; 21%-31%; P=.23; and 50%; 40%-60% vs 38%; 28%-48%; P=.07).

CONCLUSION

A late ultrasound scan performed in the third trimester increases the probability of detecting small for gestational age infants and intrauterine growth restriction with fewer additional scans reported than for the early ultrasound scan group. The overall perinatal outcome risk was comparable between the 2 groups. However, the overall sensitivity for detecting small for gestational age fetuses and intrauterine growth restriction, including in the last ultrasound scan performed before delivery, remains comparable between the late ultrasound scan and early ultrasound scan groups.

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Key Words

• intrauterine growth restriction
• perinatal mortality and morbidity
• screening
• small for gestational age
• ultrasonography

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MESH Headings

• Female
• Humans
• Pregnancy
• Birth Weight
• Fetal Growth Retardation/diagnostic imaging
• Fetal Growth Retardation/epidemiology
• Gestational Age
• Pregnancy Trimester, Third
• Ultrasonography, Prenatal/methods

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Affiliation(s)

Eric Verspyck Department of Obstetrics and Gynecology, Rouen University Hospital, Rouen, France (Drs Verspyck, Brasseur-Daudruy, Braund, and Benichou).
Caroline Thill Department of Biostatistics, Rouen University Hospital, Rouen, France (Dr Thill)
Anne Ego University Grenoble Alpes, CNRS, Public Health Department CHU Grenoble Alpes, Grenoble Institute of Engineering, TIMC-IMAG, 38000 Grenoble, France (Dr Ego); INSERM UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (EPOPé), Center for Epidemiology and Statistics Sorbonne Paris Cité (CRESS), FHU PREMA, Paris Descartes University, Paris, France (Dr Ego)
Elise Machevin Department of Obstetrics and Gynecology, Evreux Hospital, Evreux, France (Dr Machevin)
Marie Brasseur-Daudruy Department of Obstetrics and Gynecology, Rouen University Hospital, Rouen, France (Drs Verspyck, Brasseur-Daudruy, Braund, and Benichou)
Valentine Ickowicz Department of Obstetrics and Gynecology, Belvedere Hospital, Mont Saint Aignan, France (Dr Ickowicz)
Caroline Blondel Department of Obstetrics and Gynecology, Mathilde Private Clinic, Rouen, France (Dr Blondel)
Sophie Degré Department of Obstetrics and Gynecology, Le Havre Hospital, Le Havre, France (Dr Degré)
Anne Lefebure Department of Obstetrics and Gynecology, Elbeuf Hospital, Elbeuf, France (Dr Lefebure)
Sophia Braund Department of Obstetrics and Gynecology, Rouen University Hospital, Rouen, France (Drs Verspyck, Brasseur-Daudruy, Braund, and Benichou)
Jacques Benichou Department of Obstetrics and Gynecology, Rouen University Hospital, Rouen, France (Drs Verspyck, Brasseur-Daudruy, Braund, and Benichou); Inserm U1018, University of Rouen and University Paris-Saclay, Rouen, France (Dr Benichou); Department of Biostatistics, Rouen University Hospital, Rouen, France (Dr Benichou)

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Impact of Action Taken in Response to Stillbirth Audit: A Success Story

Objectives

Study the impact of intra-facility interventions on the modifiable factors causing stillbirths (SB), using point-of-care quality improvement (POCQI) methodology.

Material and Methods

Stillbirth data during the 9 months pre-intervention period were reviewed to identify the common preventable causes. Two interventions, namely, ultrasound at 34-36 weeks gestation and intrapartum monitoring on a common customized labor chart for all health-care providers, were done. Post-intervention data were collected to observe the impact of the interventions.

Results

The stillbirth rate reduced from 212/5940 deliveries (35.7/1000) in the pre-intervention period to 165/5993 deliveries (27.7/1000) in the post-intervention period (p = 0.011). The intra-facility failure to identify FGR significantly reduced in the post-intervention group (p = 0.033), leading to 63% (RR 0.37) reduction in its risk. Using a common customized labor chart led to a significant decline in the inadequate monitoring as a provider-related cause of stillbirth (p < 0.001) leading to its 42% decline as contributor to modifiable cause of SB (RR 0.48).

Conclusion

Reviewing the perinatal death surveillance response (PDSR) data, identifying gaps in care, and using improvement methodology for instituting corrective measures play an important role in reducing intramural stillbirths.

Directive clinique no 442 : Retard de croissance intra-utérin : Dépistage, diagnostic et prise en charge en contexte de grossesse monofœtale

OBJECTIF

Le retard de croissance intra-utérin est une complication obstétricale fréquente qui touche jusqu'à 10 % des grossesses dans la population générale et qui est le plus souvent due à une pathologie placentaire sous-jacente. L'objectif de la présente directive clinique est de fournir des déclarations sommaires et des recommandations pour appuyer un protocole clinique de dépistage, diagnostic et prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes.

POPULATION CIBLE

Toutes les patientes enceintes menant une grossesse monofœtale. BéNéFICES, RISQUES ET COûTS: La mise en application des recommandations de la présente directive devrait améliorer la compétence des cliniciens quant à la détection du retard de croissance intra-utérin et à la réalisation des interventions indiquées. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches effectuées jusqu'en septembre 2022 dans les bases de données PubMed, Medline, CINAHL et Cochrane Library en utilisant un vocabulaire contrôlé au moyen de termes MeSH pertinents (fetal growth retardation and small for gestational age) et de mots-clés (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Seuls les résultats de revues systématiques, d'essais cliniques randomisés ou comparatifs et d'études observationnelles ont été retenus. La littérature grise a été obtenue par des recherches menées dans des sites Web d'organismes s'intéressant à l'évaluation des technologies dans le domaine de la santé et d'organismes connexes, dans des collections de directives cliniques, des registres d'essais cliniques et des sites Web de sociétés de spécialité médicale nationales et internationales. MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Obstétriciens, médecins de famille, infirmières, sages-femmes, spécialistes en médecine fœto-maternelle, radiologistes et autres professionnels de la santé qui prodiguent des soins aux patientes enceintes. RéSUMé POUR TWITTER: Mise à jour de la directive sur le dépistage, le diagnostic et la prise en charge du retard de croissance intra-utérin pour les grossesses à risque ou atteintes. DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS: Prédiction du retard de croissance intra-utérin Prévention du retard de croissance intra-utérin Détection du retard de croissance intra-utérin Examens en cas de retard de croissance intra-utérin soupçonné Prise en charge du retard de croissance intra-utérin précoce Prise en charge du retard de croissance intra-utérin tardif Prise en charge du post-partum et consultations préconception.

Guideline No. 442: Fetal Growth Restriction: Screening, Diagnosis, and Management in Singleton Pregnancies

OBJECTIVE

Fetal growth restriction is a common obstetrical complication that affects up to 10% of pregnancies in the general population and is most commonly due to underlying placental diseases. The purpose of this guideline is to provide summary statements and recommendations to support a clinical framework for effective screening, diagnosis, and management of pregnancies that are either at risk of or affected by fetal growth restriction.

TARGET POPULATION

All pregnant patients with a singleton pregnancy.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline should increase clinician competency to detect fetal growth restriction and provide appropriate interventions.

EVIDENCE

Published literature in English was retrieved through searches of PubMed or MEDLINE, CINAHL, and The Cochrane Library through to September 2022 using appropriate controlled vocabulary via MeSH terms (fetal growth retardation and small for gestational age) and key words (fetal growth, restriction, growth retardation, IUGR, FGR, low birth weight, small for gestational age, Doppler, placenta, pathology). Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. Grey literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Table A1 for definitions and Table A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, radiologists, and other health care providers who care for pregnant patients.

TWEETABLE ABSTRACT

Updated guidelines on screening, diagnosis, and management of pregnancies at risk of or affected by FGR.

SUMMARY STATEMENTS

RECOMMENDATIONS: Prediction of FGR Prevention of FGR Detection of FGR Investigations in Pregnancies with Suspected Fetal Growth Restriction Management of Early-Onset Fetal Growth Restriction Management of Late-Onset FGR Postpartum management and preconception counselling.

Personalized stratification of pregnancy care for small for gestational age neonates from biophysical markers at midgestation

BACKGROUND

Antenatal identification of pregnancies at high risk of delivering small for gestational age neonates may improve the management of the condition and reduce the associated adverse perinatal outcomes. In a series of publications, we have developed a new competing-risks model for small for gestational age prediction, and we demonstrated that the new approach has a superior performance to that of the traditional methods. The next step in shaping the appropriate management of small for gestational age is the timely assessment of these high-risk pregnancies according to an antenatal stratification plan.

OBJECTIVE

This study aimed to demonstrate the stratification of pregnancy care based on individual patient risk derived from the application of the competing-risks model for small for gestational age that combines maternal factors with sonographic estimated fetal weight and uterine artery pulsatility index at midgestation.

STUDY DESIGN

This was a prospective observational study of 96,678 singleton pregnancies undergoing routine ultrasound examination at 19 to 24 weeks of gestation, which included recording of estimated fetal weight and measurement of uterine artery pulsatility index. The competing-risks model for small for gestational age was used to create a patient-specific stratification curve capable to define a specific timing for a repeated ultrasound examination after 24 weeks. We examined different stratification plans with the intention of detecting approximately 80%, 85%, 90%, and 95% of small for gestational age neonates with birthweight <3rd and <10th percentiles at any gestational age at delivery until 36 weeks; all pregnancies would be offered a routine ultrasound examination at 36 weeks.

RESULTS

The stratification of pregnancy care for small for gestational age can be based on a patient-specific stratification curve. Factors from maternal history, low estimated fetal weight, and increased uterine artery pulsatility index shift the personalized risk curve toward higher risks. The degree of shifting defines the timing for assessment for each pregnancy. If the objective of our antenatal plan was to detect 80%, 85%, 90%, and 95% of small for gestational age neonates at any gestational age at delivery until 36 weeks, the median (range) proportions (percentages) of population examined per week would be 3.15 (1.9-3.7), 3.85 (2.7-4.5), 4.75 (4.0-5.4), and 6.45 (3.7-8.0) for small for gestational age <3rd percentile and 3.8 (2.5-4.6), 4.6 (3.6-5.4), 5.7 (3.8-6.4), and 7.35 (3.3-9.8) for small for gestational age <10th percentile, respectively.

CONCLUSION

The competing-risks model provides an effective personalized continuous stratification of pregnancy care for small for gestational age which is based on individual characteristics and biophysical marker levels recorded at the midgestation scan.

Fetal Growth Velocity according to the Mode of Assisted Conception

INTRODUCTION

Pregnancies conceived through assisted reproductive techniques (ARTs) are on the rise worldwide and have been associated with a higher risk of placental-related disease in the third trimester.

METHODS

A cohort was created of singleton pregnancies after assisted reproduction, admitted at our institution for delivery, between January 2020 and August 2022. Fetal growth velocity from the second trimester to delivery was compared against a gestational-age-matched group of pregnancies spontaneously conceived according to the origin of the selected oocyte (i.e., autologous vs. donated).

RESULTS

125 singleton pregnancies conceived through ART were compared to 315 singleton spontaneous conceptions. Overall, after adjusting for possible confounders, multivariate analysis demonstrated that ART pregnancies had a significantly lower estimated fetal weight (EFW) z-velocity from the second trimester to delivery (adjusted mean difference = -0.002; p = 0.035) and a higher frequency of EFW z-velocity in the lowest decile (adjusted OR = 2.32 [95% CI, 1.15-4.68]). Also, when ART pregnancies were compared according to the type of oocyte, those conceived with donated oocytes showed a significantly lower EFW z-velocity from the second trimester to delivery (adjusted mean difference = -0.008; p = 0.001) and a higher frequency of EFW z-velocity in the lowest decile (adjusted OR = 5.33 [95% CI, 1.34-21.5]).

CONCLUSIONS

Pregnancies achieved through ART exhibit a pattern of lower growth velocity across the third trimester, especially those conceived with donated oocytes. The former represents a sub-group at the highest risk of placental dysfunction that may warrant closer follow-up.

Feasibility of extended ultrasound examination of the fetal brain between 24 and 37 weeks' gestation in low-risk pregnancies

OBJECTIVES

To assess the feasibility of identifying fetal brain structures and anatomic landmarks included in the anterior complex (AC) and posterior complex (PC), as well as the proximal hemisphere (PH).

METHODS

This was a prospective observational multicenter study of healthy pregnant women evaluated by ultrasound screening at 24 to 36 + 6 weeks' gestation. Six physicians performed transabdominal ultrasound, to obtain the planes required to visualize the AC, PC, and PH. Blind analysis by an expert and non-expert operator in fetal neurosonography was used to assess the structures included in each plane view.

RESULTS

In the population studied (n=366), structure detection rates for AC were over 95 %, with an agreement of 96 % when comparing expert and non-expert examiners. Visualization of the corpus callosum crossing the midline was detected in over 97 and 96 % of cases for the AC and PC, respectively, with an agreement of over 96 %. The PH plane, particularly through the posterior access via the mastoid fontanelle, enabled visualization of the proximal anatomical structures in almost 95 % of cases. Detection of the corpus callosum through the AC and PC, both proximal/distal germinal matrix (AC) and proximal Sylvian fissure through the anterior access (PH) in the 24-25 + 6, 26-31 + 6 and 32-36 + 6 weeks' gestation groups were successful in over 96 % of cases with high level of agreement.

CONCLUSIONS

Inclusion of AC, PC, and PH later in pregnancy proves feasible with a high level of agreement between both expert and non-expert operators.

Dynamic growth changes in fetal growth restriction using serial ultrasonographic biometry and umbilical artery doppler: The multicenter PORTO study

OBJECTIVE

To describe the growth dynamics of fetuses with initial fetal growth restriction (FGR) later outgrowing the 10th centile for estimated fetal weight with respect to perinatal outcomes and maternal factors.

METHODS

A multicenter prospective study recruited 1116 patients for ultrasound surveillance between 2010 and 2012. All pregnancies were growth-restricted singleton gestations between 24 + 0 and 36 + 0 weeks. Biometry and Doppler analysis were carried out, and delivery and adverse perinatal outcomes were recorded.

RESULTS

A total of 193 (17%) fetuses outgrew their diagnosis of initial FGR (surpassed the 10th centile) on their last sonogram before delivery. These fetuses were termed "growers," to compare with the true FGR group. The mothers of "growers" were less likely to be smokers (14% vs 25%, P = 0.0001) or affected by hypertensive pregnancy complications (5.2% vs 15%, P = 0.001). Of the growers, 49 (25%) had an abnormal umbilical artery Doppler; however, in most cases (33/49, 67%), this was a single episode of raised umbilical artery pulsatility index, which subsequently normalized.

CONCLUSION

There were dynamic growth changes in FGR fetuses, with 17% outgrowing their original diagnosis. Positive growth spurts more commonly occurred in healthy mothers. Once a fetus had outgrown the 10th centile, antenatal surveillance could be decreased.

Comparative Diagnostic Performance of Estimated Fetal Weight and Isolated Abdominal Circumference for the Detection of Fetal Growth Restriction

OBJECTIVES

To describe the comparative incidence, detection of small-for-gestational age (SGA), and composite perinatal morbidity (CPM) associated with diagnostic criteria of fetal growth restriction (FGR) by estimated fetal weight (EFW) <10% with those with isolated abdominal circumference (AC) measurements <10%.

METHODS

We performed a retrospective cohort study of 1587 patients receiving prenatal care and delivery at our institution. We included all patients with ultrasounds and delivery outcomes available, and excluded terminations, second trimester losses, and pregnancies without ultrasounds. EFW was calculated from Hadlock and use of the Duryea centiles, and AC from Hadlock's reference curves. We determined SGA at birth and defined CPM as birthweight less than 3% or birthweight less than 10% with neonatal morbidity.

RESULTS

Of 1587 patients, 28 (1.8%) were classified as FGR by EFW <10%. Three of 12 patients with isolated AC <10% developed EFW <10% later in pregnancy (25%). The performance of each diagnostic criteria were comparable for the outcomes of SGA and CPM, with similar sensitivities, but with decreased specificity for SGA outcome, and an increased false positive rate for patients classified as FGR by isolated AC <10, with a tradeoff of decreased false negatives.

CONCLUSIONS

Broadening the diagnosis of FGR to include patients with isolated AC <10 did not significantly increase the detection of pregnancies at risk for SGA or CPM. Our conclusions may be limited by a lack of statistical power given a low frequency of SGA and CPM.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Performance of a risk factor-based approach in the detection of small for gestational age neonates: A cohort study

BACKGROUND

Antenatal detection of fetal growth restriction allows the opportunity to increase surveillance and initiate intervention to prevent adverse outcomes. Detection of small for gestational age (SGA) fetuses with risk factor screening and selective ultrasonography is the standard of care in Australia, but evidence regarding performance is lacking.

AIMS

To evaluate the diagnostic performance of a risk factor-based screening approach in detection of SGA neonates.

MATERIALS AND METHODS

Retrospective cohort study conducted in a metropolitan maternity service, including all consecutive singleton deliveries over 20 weeks gestation from July 2016 to December 2017, and excluding terminations of pregnancy. An SGA neonate was defined by birthweight below the tenth percentile according to Australian reference ranges. Antenatally detected SGA cases were defined by estimated fetal weight or abdominal circumference below the tenth percentile for gestational age, or abnormal symphysio-fundal height. The diagnostic accuracy of the screening protocol was calculated using detection rates and false-positive rates.

RESULTS

There were 13 384 singleton pregnancies included. There were 1330 infants (10.0%) who were SGA at birth. Antenatal detection rate of SGA neonates was 39.6% (95% confidence interval (CI) 37.0-42.3%), with a false-positive rate of 10.2% (95% CI 9.6-10.7%). There were 10 266 pregnancies (77.0%) which had at least one risk factor for an SGA infant. Of these, 6650 (64.8%) underwent at least one fetal growth ultrasound after 24 weeks gestation.

CONCLUSIONS

Antenatal recognition of poor fetal growth is suboptimal using our current screening protocol. Three-quarters of pregnancies demonstrated risk factors for delivering an SGA infant, but growth ultrasonography may be underutilised.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prediction of late-onset fetal growth restriction by umbilical artery velocities at 37 weeks of gestation: a cross-sectional study

OBJECTIVE

To explore the predictive capacity of umbilical artery (UA) velocities at 37 weeks of gestation in identifying fetal growth restriction (FGR).

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

We retrospectively recruited 569 fetuses in the study. Thirty-nine FGR infants and 57 small-for-gestational-age (SGA) infants with normal UA Doppler at 37 weeks, as the study groups and 473 adequate-for-gestational-age (AGA) infants as a control group in a tertiary referral centre.

METHODS

All the parameters of UA velocities, including the UA end-diastolic velocity (UA-EDV), UA peak systolic velocity (UA-PSV), UA mean diastolic velocity (UA-MDV) and UA time-averaged maximum velocity (UA-TAMXV), and UA Doppler were measured at approximately 37 weeks of gestation.

RESULTS

Among the FGR, SGA and AGA groups, the UA-MDV, UA-TAMXV, UA-PSV and UA-EDV decreased with the loss of fetal weight. Multivariate logistic regression analyses showed that the UA-TAMXV was an independent predicting factor of FGR. It had a moderate predictive value for FGR. The area under the receiver operating characteristic curve was 0.82 (95% CI: 0.79 to 0.85).

CONCLUSIONS

The UA velocities decreased with the loss of fetal weight among the FGR, SGA and AGA groups and the UA-TAMXV was independently predictive of FGR. The results suggest that the UA-TAMXV might be a new parameter to predict FGR prior to delivery.

Fetal growth restriction and stillbirth: Biomarkers for identifying at risk fetuses

Fetal growth restriction (FGR) is a major cause of stillbirth, prematurity and impaired neurodevelopment. Its etiology is multifactorial, but many cases are related to impaired placental development and dysfunction, with reduced nutrient and oxygen supply. The fetus has a remarkable ability to respond to hypoxic challenges and mounts protective adaptations to match growth to reduced nutrient availability. However, with progressive placental dysfunction, chronic hypoxia may progress to a level where fetus can no longer adapt, or there may be superimposed acute hypoxic events. Improving detection and effective monitoring of progression is critical for the management of complicated pregnancies to balance the risk of worsening fetal oxygen deprivation in utero, against the consequences of iatrogenic preterm birth. Current surveillance modalities include frequent fetal Doppler ultrasound, and fetal heart rate monitoring. However, nearly half of FGR cases are not detected in utero, and conventional surveillance does not prevent a high proportion of stillbirths. We review diagnostic challenges and limitations in current screening and monitoring practices and discuss potential ways to better identify FGR, and, critically, to identify the “tipping point” when a chronically hypoxic fetus is at risk of progressive acidosis and stillbirth.

Fetal weight projection model to define growth velocity and validation against pregnancy outcome in a cohort of serially scanned pregnancies

OBJECTIVE

Fetal growth assessment is central to good antenatal care, yet there is a lack of definition of normal and abnormal fetal growth rate which can identify pregnancies at risk of adverse outcome. The aim of this study was to develop and test a model for defining normal limits of growth velocity which are specific to the fetal weight measurement interval.

METHODS

The cohort consisted of 102 138 singleton pregnancies which underwent at least two third-trimester measurements of ultrasound estimated fetal weight (EFW), usually carried out because routine early-pregnancy risk assessment had indicated an increased risk of fetal growth restriction. We projected the EFW from the first of each consecutive measurement pair along its own centile rank to the gestational age of the second scan. Normal growth was defined as the second EFW being within a weight range based on limits derived by partial receiver-operating-characteristics-curve (pROC) analyses for small-for-gestational-age (SGA; < 10^th  centile) and large-for-gestational-age (LGA; > 90^th  centile) birth weight. The limits were measurement-interval specific and calculated for a fixed false-positive rate (FPR) of 10%. The resultant normal, slow and accelerated growth rates calculated from consecutive EFW pairs were evaluated against the following predefined perinatal outcome measures: stillbirth, neonatal death, SGA and LGA at birth, 5-min Apgar score < 7 and admission to the neonatal intensive care unit. Slow growth based on the last two scans was compared with SGA fetal weight (EFW < 10^th  centile) at the last scan and association with stillbirth risk was assessed, expressed as relative risk (RR) with 95% CI.

RESULTS

The optimal cut-off limits for normal growth rate between consecutive scans varied according to the length of the measurement interval, with an average of -8.0% for slow growth and + 9.3% for accelerated growth at a fixed FPR of 10%. Slow growth between random consecutive scan pairs was associated significantly with all predefined outcome measures including stillbirth (RR, 2.19; 95% CI, 1.84-2.53) and neonatal death (RR, 2.28; 95% CI, 1.60-3.13). Accelerated growth was associated with LGA at birth (RR, 2.15; 95% CI, 2.10-2.20), while normal growth was protective of all adverse outcome measures. Slow growth between the last two scans (which were performed at a median gestational age of 33 + 1 to 36 + 4 weeks) and SGA at the last scan were each predictors of stillbirth, and stillbirth risk was highest when both were present (RR, 2.65; 95% CI, 1.67-4.20). However, 66.2% of pregnancies with slow growth were not SGA at the last scan and these cases also had an increased risk of stillbirth (RR, 2.07; 95% CI, 1.40-3.05).

CONCLUSION

Fetal growth velocity defined by projected, measurement-interval specific fetal weight limits is associated independently with perinatal outcome and should be used for antenatal surveillance in addition to assessment by fetal size. © 2022 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Impact of suspected late-onset fetal growth restriction on obstetrical interventions and perinatal outcomes at term; a retrospective cohort study

OBJECTIVES

First, assess accuracy of late third trimester universal fetal growth screening in high risk nulliparous women with a singleton in vertex presentation at term. Second, assess instrumental delivery rates and perinatal outcomes in this population.

STUDY DESIGN

Single centre retrospective cohort study in a teaching hospital, The Netherlands.

RESULTS

In a cohort of 1902 pregnancies, growth ultrasound after 33 weeks was moderately accurate in detecting children with a birthweight below the 10th centile with a sensitivity of 46.2% and a false positive rate of 4.7%. Induction of labour followed an antenatal suspicion of FGR more often than in the group with normal expected fetal weight (73.4% vs 52.6% OR 2.49 (1.88-3.3)) as could be expected from application of guidelines. The caesarean section rates was lowest in the group with suspected FGR compared to the group with expected normal fetal weight (15.2% vs 22.1% OR 0.63 (0.45-0.9)). There were no differences between both groups in rates of composite severe adverse perinatal outcome (0.7% vs 0.8% OR 0.87 (0.2-3.93)).

CONCLUSIONS

The detection of growth restriction using universal screening in term high risk nulliparous women with a singleton in vertex position is moderate. Despite this, caesarean section rates were not increased and perinatal outcomes were similar when compared to that found in the randomized controlled trial on which the recommendation for induction of labour for suspected term FGR is based. This supports universal late third trimester fetal growth screening in pregnancies under consultant-led care in the two tiers Dutch obstetrical system.

Prenatal prediction of very late onset small-for-gestational age newborns in low-risk pregnancies

OBJECTIVE

To find a multivariate model for predicting small-for-gestational age newborns at 36 weeks' gestation by using clinical, biochemical and ultrasound measurements.

MATERIALS AND METHODS

We evaluated 564 low-risk pregnant women and recorded maternal age, maternal body mass index, maternal mean blood pressure, soluble fms-like tyrosine kinase-1 (multiples of the median), placental growth factor (multiples of the median), soluble fms-like tyrosine kinase-1/placental growth factor ratio, estimated fetal weight centile and mean uterine artery pulsatility index at 36 weeks. Binary logistic regression was used. Statistical significance was set at 95% level (p < 0.05).

RESULTS

We found three multivariate models showing relatively small differences in predictive capability. Model 1 only included estimated fetal weight centiles (area under the curve [AUC] 0.86; R2 = 0.42; p < 0.0001), Model 2 estimated fetal weight centiles and placental growth factor (multiples of the median) (AUC 0.87; R2 = 0.44; p < 0.0001) and Model 3 estimated fetal weight centiles, placental growth factor (multiples of the median) and mean uterine artery pulsatility index (AUC 0.88; R2 = 0.45; p < 0.0001).

CONCLUSION

Small-for-gestational age at delivery may be predicted by using a multivariate formula. The inclusion of parameters other than estimated fetal weight centile at 36 weeks' gestation modestly improves the predictive capability of the model. Clinical decisions should consider whether or not these slight differences deserve a change in current strategies.

Detection and clinical outcome of small-for-gestational-age fetuses in the third trimester-A comparison between routine ultrasound examination and examination on indication

INTRODUCTION

Fetal growth restriction is a major risk factor for adverse perinatal outcome. As most of the growth-restricted fetuses are small for gestational age (SGA), an efficient antenatal screening method for SGA fetuses would have a major impact on perinatal health. The aim of this study was to compare the SGA prediction rate achieved with third-trimester routine ultrasound estimation of fetal weight (EFW) with that obtained using ultrasound examination on indication. The secondary aim was to evaluate the clinical outcome in relation to the SGA screening method.

MATERIAL AND METHODS

During 1995-2009, two perinatal centers in southern Sweden offered routine ultrasound examination at 32-34 gestational weeks to 99 265 women with singleton pregnancies. Of these, 59 452 (60%) underwent the ultrasound examination. The other population, comprising 24 868 pregnancies, was cared for in another three centers that used a risk-based method with ultrasound examinations on indication only. Of them, 5792 (23%) underwent ultrasound examination at 32-36 gestational weeks. The deviation in the EFW from the expected one was expressed as the EFW z-score, SGA EFW being defined as the EFW z-score less than -2. SGA prediction ability was assessed by receiver operating characteristic (ROC) curves. Crude and adjusted risk ratios were calculated for selected variables of perinatal outcome when comparing the populations.

RESULTS

The SGA prediction ability for routine ultrasound was high, area under the ROC curve was 0.90 (95% CI 0.89-0.91). For an EFW z-score of -1, the sensitivity was 67.3% and specificity was 90.5% among routinely screened pregnancies; corresponding numbers in the ultrasound on indication population were 34.3% and 96.6%. The screened population had a lower risk of preterm birth, birthweight z-score less than -3, and Apgar score less than 7 at 5 min with adjusted risk ratios 0.87 (95% CI 0.82-0.92), 0.75 (95% CI 0.61-0.92), and 0.77 (95% CI 0.68-0.87), respectively. No difference in perinatal mortality was detected. There were no differences in perinatal outcome between the two subcohorts of infants born SGA.

CONCLUSIONS

Third-trimester routine ultrasound improves the detection of SGA antenatally compared with ultrasound performed on indication, but no convincing improvement in perinatal outcome was identified.

Competing risks model for prediction of small-for-gestational-age neonates from biophysical markers at 19 to 24 weeks' gestation

BACKGROUND

Antenatal identification of women at high risk to deliver small-for-gestational-age neonates may improve the management of the condition. The traditional but ineffective methods for small-for-gestational-age screening are the use of risk scoring systems based on maternal demographic characteristics and medical history and the measurement of the symphysial-fundal height. Another approach is to use logistic regression models that have higher performance and provide patient-specific risks for different prespecified cutoffs of birthweight percentile and gestational age at delivery. However, such models have led to an arbitrary dichotomization of the condition; different models for different small-for-gestational-age definitions are required and adding new biomarkers or examining other cutoffs requires refitting of the whole model. An alternative approach for the prediction of small-for-gestational-age neonates is to consider small for gestational age as a spectrum disorder whose severity is continuously reflected in both the gestational age at delivery and z score in birthweight for gestational age.

OBJECTIVE

This study aimed to develop a new competing risks model for the prediction of small-for-gestational-age neonates based on a combination of maternal demographic characteristics and medical history with sonographic estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure at 19 to 24 weeks' gestation.

STUDY DESIGN

This was a prospective observational study of 96,678 women with singleton pregnancies undergoing routine ultrasound examination at 19 to 24 weeks' gestation, which included recording of estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure. The competing risks model for small for gestational age is based on a previous joint distribution of gestational age at delivery and birthweight z score, according to maternal demographic characteristics and medical history. The likelihoods of the estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure were fitted conditionally to both gestational age at delivery and birthweight z score and modified the previous distribution, according to the Bayes theorem, to obtain an individualized posterior distribution for gestational age at delivery and birthweight z score and therefore patient-specific risks for any desired cutoffs for birthweight z score and gestational age at delivery. The model was internally validated by randomly dividing the data into a training data set, to obtain the parameters of the model, and a test data set, to evaluate the model. The discrimination and calibration of the model were also examined.

RESULTS

The estimated fetal weight was described using a regression model with an interaction term between gestational age at delivery and birthweight z score. Folded plane regression models were fitted for uterine artery pulsatility index and mean arterial pressure. The prediction of small for gestational age by maternal factors was improved by adding biomarkers for increasing degree of prematurity, higher severity of smallness, and coexistence of preeclampsia. Screening by maternal factors with estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure, predicted 41%, 56%, and 70% of small-for-gestational-age neonates with birthweights of <10th percentile delivered at ≥37, <37, and <32 weeks' gestation, at a 10% false-positive rate. The respective rates for a birthweight of <3rd percentile were 47%, 65%, and 77%. The rates in the presence of preeclampsia were 41%, 72%, and 91% for small-for-gestational-age neonates with birthweights of <10th percentile and 50%, 75%, and 92% for small-for-gestational-age neonates with birthweights of <3rd percentile. Overall, the model was well calibrated. The detection rates and calibration indices were similar in the training and test data sets, demonstrating the internal validity of the model.

CONCLUSION

The performance of screening for small-for-gestational-age neonates by a competing risks model that combines maternal factors with estimated fetal weight, uterine artery pulsatility index, and mean arterial pressure was superior to that of screening by maternal characteristics and medical history alone.

Fetal growth restriction: underdiagnosed condition with non-optimal screening

BACKGROUND

Fetal Growth restriction (FGR) is the pathological failure of a fetus to reach its biologically determined growth potential. Detection of FGR fetuses is a universally agreed key objective of antenatal care. Antenatal detection of FGR has undeniable benefits, juggling between intensive fetal surveillance and optimized timing of delivery; it reduces adverse perinatal outcomes by up to four-fold. However, FGR is still widely underdiagnosed. We aimed to identify the prevalence of FGR diagnosis in our wards and study the impact of the 2013 published French guidelines on the detection rate of FGR. The secondary objective aimed to highlight the factors of suboptimal screening in the population of non-diagnosed FGR fetuses and emphasize the screening method that led to antenatal diagnosis of FGR.

MATERIALS AND METHODS

We conducted a retrospective study at a single tertiary maternity center in Lyon-France, the Femme Mère Enfant Hospital, including the exhaustive population of FGR born after 24 + 0 weeks of gestation from 1 January 2011 to 31 December 2017. FGR was defined combining the neonatal and antenatal consensus-based definitions for early and late FGR in absence of congenital anomalies, excluding small for gestational age fetuses. For all FGR fetuses, we compared the antenatal detection rate of FGR during 2011-2013 to 2015-2017, since the French guidelines were published in December 2013. When FGR fetuses underwent an antenatal diagnosis of FGR, we retrospectively collected the characteristics that led to the diagnosis. When fetuses were not diagnosed as FGR, we retrospectively reviewed the implementation of the recommended screening method, enabling to evaluate whether screening was optimal or not. Statistical analysis was performed in July 2018, and statistical significance was regarded as a p-value <.05.

RESULTS

Over the seven-year period, and among 31,052 newborns, 1020 (3.3%) infants were identified as FGR and met the inclusion criteria. The detection rate of FGR was similar before and after publication of the French Guidelines related to FGR in 2013. Indeed, 50.8% (201/395) FGR were diagnosed between 2011 and 2013 versus 52.6% (245/465) between 2015 and 2017 (p = .59). In the population of non-diagnosed FGR infants, screening was suboptimal in 80%. Symphysis-fundal height (SFH) was not measured in 10.7%, with no difference before and after 2014 (7.3 versus 11.8% p = .11). Ultrasound examination for fetal biometry had not been prescribed in spite of abnormal SFH in 47.7% of undiagnosed FGR infants. Diagnosis has been missed in 11.5% of infants because of misinterpretation of the estimated fetal weight's centile.

CONCLUSION

FGR is widely underdiagnosed. However, the limited performances can partially be explained by the regular misuse of screening method in clinical practice. Despite the systematic third trimester ultrasound screening, the detection rate of FGR was similar to the one reported in the medical literature. The timing of routine third trimester ultrasound in low-risk women may be rethought.

Prediction of Late-Onset Small for Gestational Age and Fetal Growth Restriction by Fetal Biometry at 35 Weeks and Impact of Ultrasound-Delivery Interval: Comparison of Six Fetal Growth Standards

Small-for-gestational-age (SGA) infants have been associated with increased risk of adverse perinatal outcomes (APOs). In this work, we assess the predictive ability of the ultrasound-estimated percentile weight (EPW) at 35 weeks of gestational age to predict late-onset SGA and APOs, according to six growth standards, and whether the ultrasound–delivery interval influences the detection rate. To this purpose, we analyze a retrospective cohort study of 9585 singleton pregnancies. EPWs at 35 weeks were calculated to the customized Miguel Servet University Hospital (MSUH) and Figueras standards and the non-customized MSUH, Fetal Medicine Foundation (FMF), INTERGROWTH-21st, and WHO standards. As results of our analysis, for a 10% false positive rate, the detection rates for SGA ranged between 48.9% with the customized Figueras standard (AUC 0.82) and 60.8% with the non-customized FMF standard (AUC 0.87). Detection rates to predict SGA by ultrasound–delivery interval (1–6 weeks) show higher detection rates as intervals decrease. APOs detection rates ranged from 27.0% with FMF to 7.9% with the Figueras standard. In conclusion, the ability of EPW to predict SGA at 35 weeks is good for all standards, and slightly better for non-customized standards. The APO detection rate is significantly greater for non-customized standards.

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.

The impact of individual sonographer variation on the detection of small for gestational age fetuses using a third trimester growth scan

OBJECTIVES

Detection of small for gestational age (SGA) fetuses in a third trimester ultrasound could be affected by variation in sonographer performance.

METHODS

Retrospective analysis of all singleton, non-anomalous ultrasound examinations between 35⁺⁰ -36⁺⁶ weeks gestation, in a single institution where a universal 36-week scan is offered. Screen positive was defined as estimated fetal weight (EFW) <10th centile; SGA was birthweight <10th centile. Individual sonographers' distributions of head circumference (HC), abdominal circumference (AC) and femur length (FL) were used to assess sonographers' screen positive rate (SPR), detection rate (DR) and true positive rate (TPR). Univariate and multivariate regression analysis was performed to assess the association between the sonographers' mean and SD (SD) for HC, AC, FL and their SPR, DR and TPR.

RESULTS

There were 27 sonographers performing more than 50 examinations per year, a total of 5691 scans. The mean incidence of SGA was 10.0%. For an overall SPR of 9.4%, the overall DR was 43.8% (95% CI: 39.6% - 48.1%) and the overall TPR was 46.5% (95% CI: 42.9% - 50.2%). Higher AC scatter (SD difference up to 11.6 mm) was associated with higher SPR (P = 0.001). Lower mean FL (difference up to 3.6 mm) was associated with higher SPR (P = 0.003) and higher DR (P = 0.002). As a result, DR varied amongst different sonographers between 14.3% and 85.7% and TPR varied between 8.3% and 100.0%.

CONCLUSIONS

Monitoring of individual AC and FL distributions is a simple and effective tool for institutional quality assurance.

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.

Prenatal selection of cord blood donors according to the estimated fetal weight percentile and new approaches; results of a prospective cohort study

BACKGROUND

Umbilical cord blood (UCB) donation is becoming inefficient and we recently proposed the estimated fetal weight percentile (EFWp) ≥60th as a predictor for a prenatal selection of donors. The aim of this study is to prospectively validate this and to identify new potential prenatal predictive parameters.

STUDY DESIGN AND METHODS

Prospective cohort study of low-risk pregnancies undergoing third trimester ultrasound, whose UCB was collected at delivery (2016-2018) and compared with a historical cohort (2013-2016, N = 869). Several ultrasound parameters (EFWp, amniotic fluid, Doppler evaluation, placental thickness) were assessed ultrasound and perinatal data were collected. The association with standard of high quality of UCB was assessed by logistic regression analysis.

RESULTS

Among 297 cases, 161 (54%) were selected according to the EFWp ≥60th for UCB units' collection. Cellular criteria for banking was achieved in 27 cases (16.8%), with an average increase of 1.7 times compared to the historical cohort (9.8%, P = .009). Selecting donors according to the 60th EFWp resulted in a higher probability of collecting clinical suitable UCB (P = .025). Among prenatal and perinatal parameters, EFWp, amniotic fluid, umbilical vein (UV) velocity, newborn weight and percentile and placental weight were significantly associated with a higher cellular content. At logistic regression analysis, significant contributors of UCB collection, were EFWp at 37-38 weeks ultrasound (OR 1.04; 95% CI: 1-1.08; P = .042) and UV velocity (OR 1.14; 95% CI: 1-1.29; P = .037).

CONCLUSION

The evaluation of the EFWp equal or above 60 and the increased UV velocity can result in higher efficiency of public UCB donation programs.

Risk evaluation of fetal growth restriction by combined screening in early and mid-pregnancy

Objectives:

To assess risk of fetal growth restriction (FGR) by combined screening in early and mid-pregnancy.

Methods:

Pregnant women who received prenatal examinations and delivered in our hospital from January 2015 to January 2019 were selected and retrospectively analyzed. All women completed two ultrasonographic examinations during pregnancy, i.e. Down’s screening during early pregnancy (11-13 + 6 weeks) and prenatal color Doppler screening during mid-pregnancy (20-24 weeks). A total of 33 FGR cases were screened out, and there were 1,507 normal pregnant women. The clinical, ultrasonographic and serological indices in early and mid-pregnancy were recorded. When the false positive rate was 5%, logistic regression analysis and receiver operating characteristic (ROC) curve were used to evaluate the influencing factors and predictive values of individual and combined indices for FGR in corresponding gestational weeks. The sensitivity and specificity of the optimal cutoff value of each index as well as the combination of optimal predictive indices were found by the area under ROC curve (AUC).

Results:

When the false positive rate was 5% in the single-index screening during early pregnancy, the parity, BPD, AC, HC, and FL had statistical significances. Multivariate analysis showed that the parity and BPD had statistical significances. During mid-pregnancy, univariate analysis revealed that the parity, BMI, BPD, AC, HC, FL, UTA-PI, UTA-RI, UA-PI and UA-RI had statistical significances. BMI, AC, UTA-PI, UTA-RI, UA-PI and UA-RI had statistical significances in multivariate analysis. BMI, UTA-PI and UA-PI were risk factors for FGR, with UTA-PI being most dangerous. AUC for combined screening exceeded those for individual screenings. The best combined screening program was BPD in early pregnancy + BMI + AC + UTA-PI + UTA-RI + UA-PI + UA-RI in mid-pregnancy. The optimal cutoff value was 0.015, with the sensitivity of 83.1% and the specificity of 61.3%.

Conclusion:

The predictive efficiency of combined FGR screening in early and mid-pregnancy surpasses that of simple mid-pregnancy screening. It is recommended to use the integrated screening program in early and mid-pregnancy to predict FGR.

ACR Appropriateness Criteria® Growth Disturbances-Risk of Fetal Growth Restriction

Fetal growth restriction, or an estimated fetal weight of less than the 10th percentile, is associated with adverse perinatal outcome. Optimizing management for obtaining the most favorable outcome for mother and fetus is largely based on detailed ultrasound findings. Identifying and performing those ultrasound procedures that are most associated with adverse outcome is necessary for proper patient management. Transabdominal ultrasound is the mainstay of initial management and assessment of fetal growth. For those fetuses that are identified as small for gestational age, assessment of fetal well-being with biophysical profile and Doppler velocimetry provide vital information for differentiating those fetuses that may be compromised and may require delivery and those that are well compensated. Delivery of the pregnancy is primarily based upon the gestational age of the pregnancy and the ultrasound findings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Impact of biometric measurement error on identification of small- and large-for-gestational-age fetuses

OBJECTIVES

First, to obtain measurement-error models for biometric measurements of fetal abdominal circumference (AC), head circumference (HC) and femur length (FL), and, second, to examine the impact of biometric measurement error on sonographic estimated fetal weight (EFW) and its effect on the prediction of small- (SGA) and large- (LGA) for-gestational-age fetuses with EFW < 10^th and > 90^th percentile, respectively.

METHODS

Measurement error standard deviations for fetal AC, HC and FL were obtained from a previous large study on fetal biometry utilizing a standardized measurement protocol and both qualitative and quantitative quality-control monitoring. Typical combinations of AC, HC and FL that gave EFW on the 10^th and 90^th percentiles were determined. A Monte-Carlo simulation study was carried out to examine the effect of measurement error on the classification of fetuses as having EFW above or below the 10^th and 90^th percentiles.

RESULTS

Errors were assumed to follow a Gaussian distribution with a mean of 0 mm and SDs, obtained from a previous well-conducted study, of 6.93 mm for AC, 5.15 mm for HC and 1.38 mm for FL. Assuming errors according to such distributions, when the 10^th and 90^th percentiles are used to screen for SGA and LGA fetuses, respectively, the detection rates would be 78.0% at false-positive rates of 4.7%. If the cut-offs were relaxed to the 30^th and 70^th percentiles, the detection rates would increase to 98.2%, but at false-positive rates of 24.2%. Assuming half of the spread in the error distribution, using the 10^th and 90^th percentiles to screen for SGA and LGA fetuses, respectively, the detection rates would be 86.6% at false-positive rates of 2.3%. If the cut-offs were relaxed to the 15^th and 85^th percentiles, respectively, the detection rates would increase to 97.0% and the false-positive rates would increase to 6.3%.

CONCLUSIONS

Measurement error in fetal biometry causes substantial error in EFW, resulting in misclassification of SGA and LGA fetuses. The extent to which improvement can be achieved through effective quality assurance remains to be seen but, as a first step, it is important for practitioners to understand how biometric measurement error impacts the prediction of SGA and LGA fetuses. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Value of routine ultrasound examination at 35-37 weeks' gestation in diagnosis of non-cephalic presentation

OBJECTIVE

Undiagnosed non-cephalic presentation in labor carries increased risks for both the mother and baby. Routine pregnancy care based on maternal abdominal palpation fails to detect the majority of cases of non-cephalic presentation. The aim of this study was to report the incidence of non-cephalic presentation at a routine scan at 35 + 0 to 36 + 6 weeks' gestation and the subsequent management of such pregnancies.

METHODS

This was a retrospective analysis of prospectively collected data in 45 847 singleton pregnancies that had undergone routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. Patients with breech or transverse/oblique presentation were divided into two groups; first, those who would have elective Cesarean section for fetal or maternal indications other than the abnormal presentation, and, second, those who would potentially require external cephalic version (ECV). The latter group was reassessed after 1-2 weeks and, if there was persistence of abnormal presentation, the parents were offered the option of ECV or elective Cesarean section at 38-40 weeks' gestation. Multivariable logistic regression analysis was carried out to determine which of the factors from maternal and pregnancy characteristics provided a significant contribution in the prediction of, first, non-cephalic presentation at the 35 + 0 to 36 + 6-week scan, second, successful ECV from non-cephalic to cephalic presentation, and, third, spontaneous rotation from non-cephalic to cephalic presentation that persisted until delivery.

RESULTS

First, at 35 + 0 to 36 + 6 weeks, the fetal presentation was cephalic in 43 416 (94.7%) pregnancies, breech in 1987 (4.3%) and transverse or oblique in 444 (1.0%). Second, multivariable analysis demonstrated that the risk of non-cephalic presentation increased with increasing maternal age and weight, decreasing height and earlier gestational age at scan, was higher in the presence of placenta previa, oligohydramnios or polyhydramnios and in nulliparous than parous women, and was lower in women of South Asian or mixed racial origin than in white women. Third, 22% of cases of non-cephalic presentation were not eligible for ECV because of planned Cesarean section for indications other than the malpresentation. Fourth, of those eligible for ECV, only 48.5% (646/1332) agreed to the procedure, which was successful in 39.0% (252/646) of cases. Fifth, the chance of successful ECV increased with increasing maternal age and was lower in nulliparous than parous women. Sixth, in 33.9% (738/2179) of pregnancies with non-cephalic presentation in which successful ECV was not carried out, there was subsequent spontaneous rotation to cephalic presentation. Seventh, the chance of spontaneous rotation from non-cephalic to cephalic presentation increased with increasing interval between the scan and delivery, decreased with increasing birth-weight percentile, was higher in women of black than those of white racial origin, if presentation was transverse or oblique rather than breech and if there was polyhydramnios, and was lower in nulliparous than parous women and in the presence of placenta previa. Eighth, in 109 (0.3%) cephalic presentations, there was subsequent rotation to non-cephalic presentation and, in 41% of these, the diagnosis was made during labor. Ninth, of the total 2431 cases of non-cephalic presentation at the time of the scan, presentation at birth was cephalic in 985 (40.5%); in 738 (74.9%) this was due to spontaneous rotation and in 247 (25.1%) this was due to successful ECV. Tenth, prediction of non-cephalic presentation at the 35 + 0 to 36 + 6-week scan and successful ECV from maternal and pregnancy factors was poor, but prediction of spontaneous rotation from non-cephalic to cephalic presentation that persisted until delivery was moderately good and this could be incorporated in the counseling of women prior to ECV.

CONCLUSIONS

The problem of unexpected non-cephalic presentation in labor can, to a great extent, be overcome by a routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. The incidence of non-cephalic presentation at the 35 + 0 to 36 + 6-week scan was about 5%, but, in about 40% of these cases, the presentation at birth was cephalic, mainly due to subsequent spontaneous rotation and, to a lesser extent, as a consequence of successful ECV. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Two-stage approach for prediction of small-for-gestational-age neonate and adverse perinatal outcome by routine ultrasound examination at 35-37 weeks' gestation

BACKGROUND

Justification of prenatal screening for small-for-gestational-age (SGA) fetuses near term is based on, first, evidence that such fetuses/neonates are at increased risk of stillbirth and adverse perinatal outcome, and, second, the expectation that these risks can be reduced by medical interventions, such as early delivery. However, there are no randomized studies demonstrating that routine screening for SGA fetuses and appropriate interventions in the high-risk group can reduce adverse perinatal outcome. Before such meaningful studies can be undertaken, it is essential that the best approach for effective identification of SGA neonates is determined, and that the contribution of SGA neonates to the overall rate of adverse perinatal outcome is established. In a previous study of pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation, we found that, first, screening by estimated fetal weight (EFW) < 10^th percentile provided poor prediction of SGA neonates and, second, prediction of > 85% of SGA neonates requires use of EFW < 40^th percentile.

OBJECTIVES

To examine the contribution of SGA fetuses to the overall rate of adverse perinatal outcome and, to propose a two-stage approach for prediction of a SGA neonate at routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation.

METHODS

This was a prospective study of 45 847 singleton pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation. First, we examined the relationship between birth-weight percentile and adverse perinatal outcome, defined as stillbirth, neonatal death or admission to the neonatal unit for ≥ 48 h. Second, we used a two-stage approach for prediction of a SGA neonate and adverse perinatal outcome; in the first stage, fetal biometry was used to distinguish between pregnancies at very low risk (EFW ≥ 40^th percentile) and those at increased risk (EFW < 40^th percentile) and, in the second stage, the pregnancies with EFW < 40^th percentile were stratified into high-, intermediate- and low-risk groups based on the results of EFW and pulsatility index in the uterine arteries, umbilical artery and fetal middle cerebral artery. Different percentiles of EFW and Doppler indices were used to define each risk category, and the performance of screening for a SGA neonate and adverse perinatal outcome in pregnancies delivered at ≤ 2, 2.1-4 and > 4 weeks after assessment was determined. We propose that the high-risk group would require monitoring from initial assessment to delivery, the intermediate-risk group would require monitoring from 2 weeks after initial assessment to delivery, the low-risk group would require monitoring from 4 weeks after initial assessment to delivery, and the very low-risk group would not require any further reassessment.

RESULTS

First, although in neonates with low birth weight (< 10^th percentile) the risk of adverse perinatal outcome is increased, 84% of adverse perinatal events occur in the group with birth weight ≥ 10^th percentile. Second, in screening by EFW < 10^th percentile, the predictive performance for a SGA neonate is modest for those born at ≤ 2 weeks after assessment (83% and 69% for neonates with birth weight < 3^rd and < 10^th percentiles, respectively), but poor for those born at 2.1-4 weeks (65% and 45%, respectively) and > 4 weeks (40% and 30%, respectively) after assessment. Third, improved performance of screening, especially for those delivered at > 2 weeks after assessment, is potentially achieved by a proposed new approach for stratifying pregnancies into management groups based on findings of EFW and Doppler indices (prediction of birth weight < 3^rd and < 10^th percentiles for deliveries at ≤ 2, 2.1-4 and > 4 weeks after assessment: 89% and 75%, 83% and 74%, and 88% and 82%, respectively). Fourth, the predictive performance for adverse perinatal outcome of EFW < 10^th percentile is very poor (26%, 9% and 5% for deliveries at ≤ 2, 2.1-4 and > 4 weeks after assessment, respectively) and this is improved by the proposed new approach (31%, 22% and 29%, respectively).

CONCLUSIONS

This study presents an approach for stratifying pregnancies undergoing routine ultrasound examination at 35 + 0 to 36 + 6 weeks' gestation into four management groups based on findings of EFW and Doppler indices. This approach potentially has a higher predictive performance for a SGA neonate and adverse perinatal outcome than that of screening by EFW < 10^th percentile. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Serial Third-Trimester Ultrasonography Compared With Routine Care in Uncomplicated Pregnancies: A Randomized Controlled Trial

OBJECTIVE

Among uncomplicated pregnancies, serial third-trimester ultrasound examinations identified significantly more cases with a composite of fetal growth or amniotic fluid abnormalities (27%) than did routine fundal height measurements (8%).

METHODS

Women without complications between 24 0/7 and 30 6/7 weeks of gestation were randomized (NCT0270299) to either routine care (control arm) or ultrasound examination every 4 weeks (intervention arm). The primary outcome was a composite of abnormalities of fluid volume and growth: oligohydramnios or polyhydramnios; fetal growth restriction; or large for gestational age. The secondary outcome was the presence of composite maternal or neonatal morbidity among the two groups. A total of 206 participants was needed to have 80% power to detect an increase in the primary composite outcome from 10% in control to 25% in the intervention group (baseline rate 10%; two-tailed; α=0.05; loss to follow-up 5%). All women were included in the intent-to-treat analysis. Fisher exact, χ tests, or two-sample t tests were used to assess group differences.

RESULTS

From July 11, 2016, to May 24, 2017, 852 women were screened for eligibility and 206 were randomized as follows: 102 in routine care and 104 in serial ultrasound examinations. The two groups were comparable in baseline characteristics. The primary composite outcome was significantly higher among women who were in the ultrasound examination group than the routine care group (27% vs 8%; relative risk 3.43, 95% CI 1.64-7.17); five women (95% CI 3-11) were needed to identify at least one of the composite ultrasound abnormalities. Although we were underpowered to detect a significant difference, the following secondary endpoints occurred with similar frequency in the ultrasound examination group than the routine care group: induction resulting from abnormal ultrasound examination findings (14% vs 6%), cesarean delivery in labor (5% vs 6%), and prespecified composite maternal morbidity (9% in both groups) and composite neonatal morbidity (1% vs 4%).

CONCLUSION

Among uncomplicated pregnancies between 24 0/7 and 30 6/7 weeks of gestation, serial third-trimester ultrasound examinations were significantly more likely to identify abnormalities of fetal growth or amniotic fluid than measurements of fundal height and indicated ultrasound examination. No differences in maternal and neonatal outcomes were noted, although we were underpowered for these endpoints.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02702999.

Examining the predictive accuracy of metabolomics for small-for-gestational-age babies: a systematic review

INTRODUCTION

To date, there is no robust enough test to predict small-for-gestational-age (SGA) infants, who are at increased lifelong risk of morbidity and mortality.

OBJECTIVE

To determine the accuracy of metabolomics in predicting SGA babies and elucidate which metabolites are predictive of this condition.

DATA SOURCES

Two independent researchers explored 11 electronic databases and grey literature in February 2018 and November 2018, covering publications from 1998 to 2018. Both researchers performed data extraction and quality assessment independently. A third researcher resolved discrepancies.

STUDY ELIGIBILITY CRITERIA

Cohort or nested case-control studies were included which investigated pregnant women and performed metabolomics analysis to evaluate SGA infants. The primary outcome was birth weight <10th centile-as a surrogate for fetal growth restriction-by population-based or customised charts.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two independent researchers extracted data on study design, obstetric variables and sampling, metabolomics technique, chemical class of metabolites, and prediction accuracy measures. Authors were contacted to provide additional data when necessary.

RESULTS

A total of 9181 references were retrieved. Of these, 273 were duplicate, 8760 were removed by title or abstract, and 133 were excluded by full-text content. Thus, 15 studies were included. Only two studies used the fifth centile as a cut-off, and most reports sampled second-trimester pregnant women. Liquid chromatography coupled to mass spectrometry was the most common metabolomics approach. Untargeted studies in the second trimester provided the largest number of predictive metabolites, using maternal blood or hair. Fatty acids, phosphosphingolipids and amino acids were the most prevalent predictive chemical subclasses.

CONCLUSIONS AND IMPLICATIONS

Significant heterogeneity of participant characteristics and methods employed among studies precluded a meta-analysis. Compounds related to lipid metabolism should be validated up to the second trimester in different settings.

PROSPERO REGISTRATION NUMBER

CRD42018089985.

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.

National-survey for evaluation of the best screening method of late fetal growth restriction in low risk pregnancy: A prospective study

OBJECTIVE

To compare knowledge and practices surrounding third trimester screening of fetal growth restriction (FGR) in low risk pregnancies among Portuguese Gynecologists/Obstetricians (GOs) and General Practitioners (GPs). Primary outcome was to compare the proportion of GOs that consider the need of a third trimester ultrasound (estimation of fetal weight) for screening of FGR in low risk pregnancies and the best time to perform it with the corresponding proportion of GPs.

STUDY DESIGN

We have conducted a prospective, observational cohort study based on application of surveys to GOs and GPs. Questionnaires were sent by e-mail to physicians and they filled them online. A second reminder e-mail was sent 7 days later. Recruitment was also done personally at scientific meetings. A total of 573 surveys were available for analysis, 298 corresponded to GOs and 275 to GPs. We used χ² test to compare dichotomous variables and Kruskal-Wallis test for the comparison of ordinal variables. P values <0.05 were considered statistically significant.

RESULTS

The vast majority of GOs and GPs (93%) considered that third trimester ultrasound is useful and needed for surveillance of low risk pregnancy. A higher proportion of GOs (38%) selected 35th-37th weeks as the best time to perform the ultrasound compared to GPs (10%) (p < 0.001). GOs (51%) consider that symphysis-fundus distance is a measurement with moderate accuracy for screening of FGR while GPs (61%) attribute a low accuracy (p < 0.001). Fifty percent (50%) of GOs consider that performing a third trimester ultrasound will have no impact on cesarean delivery rate for fetal distress, while 41% of GPs consider that routine ultrasound will contribute to increase this rate (p < 0.001). The majority of GPs (52%) consider that routine ultrasound will contribute to diminish the admission rate to neonatal intensive care unit while GOs revealed a dichotomy with 43% of respondents reporting that it will diminish the rate and 40% that it will have no impact.

CONCLUSION

Varied opinions among the clinicians included in our sample reflect the controversy that remains on the best screening of FGR in low risk pregnancies.