Prediction of intrauterine fetal death in small-for-gestational-age fetuses: impact of including ultrasound biometry in customized models

Gestational malnutrition, hyperemesis gravidarum, and Wernicke's encephalopathy: What is missing?

Hyperemesis gravidarum (HG), or the severe nausea and vomiting of pregnancy, is one of the most dreaded complications of gestation, affecting between 1.5% and 3.0% of pregnant women. From the late 1800s to the mid-1980s, the etiology was frequently cited to have psychological and/or-later-perhaps hormonal origins, which have numbered at least 10. Current research has unearthed a genetic basis for HG that implicates growth differentiation factor 15, insulin-like growth factor binding protein 7, and hormone receptors (namely, glial cell line-derived neurogenic factor family receptor alpha-like and the progesterone receptor). Whatever the origins of this disease, it has caused immeasurable physiological and psychological damage to women, their fetuses, and their families. The psychological trauma includes a high rate of suicidal ideation as well as posttraumatic stress disorder. Whereas the healthcare costs are substantial for the mother with HG, the lifetime costs to the neonate include that which accompanies reduced employment earnings related to cognitive compromise. Another devastating outcome of severe HG can be Wernicke's encephalopathy (WE), which has a high fetal and maternal mortality rate. Our study explored 18 current reports of HG and WE. We highlighted additional presenting features we believe also accompany, and sometimes replace, the classically taught triad components of WE: ataxia, confabulation, and nystagmus. We agree with the conclusion made by Sheehan and Ironside in 1939 that thiamin alone may not reverse WE, and we offer possible explanations. Lastly, we offer suggestions for remediation.

Identification of large-for-gestational age fetuses using antenatal customized fetal growth charts: Can we improve the prediction of abnormal labor course?

INTRODUCTION

Fetal overgrowth is an acknowledged risk factor for abnormal labor course and maternal and perinatal complications. The objective of this study was to evaluate whether the use of antenatal ultrasound-based customized fetal growth charts in fetuses at risk for large-for-gestational age (LGA) allows a better identification of cases undergoing caesarean section due to intrapartum dystocia.

MATERIAL AND METHODS

An observational study involving four Italian tertiary centers was carried out. Women referred to a dedicated antenatal clinic between 35 and 38 weeks due to an increased risk of having an LGA fetus at birth were prospectively selected for the study purpose. The fetal measurements obtained and used for the estimation of the fetal size were biparietal diameter, head circumference, abdominal circumference and femur length, were prospectively collected. LGA fetuses were defined by estimated fetal weight (EFW) >95th centile either using the standard charts implemented by the World Health Organization (WHO) or the customized fetal growth charts previously published by our group. Patients scheduled for elective caesarean section (CS) or for elective induction for suspected fetal macrosomia or submitted to CS or vacuum extraction (VE) purely due to suspected intrapartum distress were excluded. The incidence of CS due to labor dystocia was compared between fetuses with EFW >95th centile according WHO or customized antenatal growth charts.

RESULTS

Overall, 814 women were eligible, however 562 were considered for the data analysis following the evaluation of the exclusion criteria. Vaginal delivery occurred in 466 (82.9 %) women (435 (77.4 %) spontaneous vaginal delivery and 31 (5.5 %) VE) while 96 had CS. The EFW was >95th centile in 194 (34.5 %) fetuses according to WHO growth charts and in 190 (33.8 %) by customized growth charts, respectively. CS due to dystocia occurred in 43 (22.2 %) women with LGA fetuses defined by WHO curves and in 39 (20.5 %) women with LGA defined by customized growth charts (p 0.70). WHO curves showed 57 % sensitivity, 72 % specificity, 24 % PPV and 91 % NPV, while customized curves showed 52 % sensitivity, 73 % specificity, 23 % PPV and 91 % NPV for CS due to labor dystocia.

CONCLUSIONS

The use of antenatal ultrasound-based customized growth charts does not allow a better identification of fetuses at risk of CS due to intrapartum dystocia.

Prediction of adverse perinatal outcome by fetal biometry: comparison of customized and population-based standards

OBJECTIVE

To compare the predictive performance of estimated fetal weight (EFW) percentiles, according to eight growth standards, to detect fetuses at risk for adverse perinatal outcome.

METHODS

This was a retrospective cohort study of 3437 African-American women. Population-based (Hadlock, INTERGROWTH-21^st , World Health Organization (WHO), Fetal Medicine Foundation (FMF)), ethnicity-specific (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)), customized (Gestation-Related Optimal Weight (GROW)) and African-American customized (Perinatology Research Branch (PRB)/NICHD) growth standards were used to calculate EFW percentiles from the last available scan prior to delivery. Prediction performance indices and relative risk (RR) were calculated for EFW < 10^th and > 90^th percentiles, according to each standard, for individual and composite adverse perinatal outcomes. Sensitivity at a fixed (10%) false-positive rate (FPR) and partial (FPR < 10%) and full areas under the receiver-operating-characteristics curves (AUC) were compared between the standards.

RESULTS

Ten percent (341/3437) of neonates were classified as small-for-gestational age (SGA) at birth, and of these 16.4% (56/341) had at least one adverse perinatal outcome. SGA neonates had a 1.5-fold increased risk of any adverse perinatal outcome (P < 0.05). The screen-positive rate of EFW < 10^th percentile varied from 6.8% (NICHD) to 24.4% (FMF). EFW < 10^th percentile, according to all standards, was associated with an increased risk for each of the adverse perinatal outcomes considered (P < 0.05 for all). The highest RRs associated with EFW < 10^th percentile for each adverse outcome were 5.1 (95% CI, 2.1-12.3) for perinatal mortality (WHO); 5.0 (95% CI, 3.2-7.8) for perinatal hypoglycemia (NICHD); 3.4 (95% CI, 2.4-4.7) for mechanical ventilation (NICHD); 2.9 (95% CI, 1.8-4.6) for 5-min Apgar score < 7 (GROW); 2.7 (95% CI, 2.0-3.6) for neonatal intensive care unit (NICU) admission (NICHD); and 2.5 (95% CI, 1.9-3.1) for composite adverse perinatal outcome (NICHD). Although the RR CIs overlapped among all standards for each individual outcome, the RR of composite adverse perinatal outcome in pregnancies with EFW < 10^th percentile was higher according to the NICHD (2.46; 95% CI, 1.9-3.1) than the FMF (1.47; 95% CI, 1.2-1.8) standard. The sensitivity for composite adverse perinatal outcome varied substantially between standards, ranging from 15% for NICHD to 32% for FMF, due mostly to differences in FPR; this variation subsided when the FPR was set to the same value (10%). Analysis of AUC revealed significantly better performance for the prediction of perinatal mortality by the PRB/NICHD standard (AUC = 0.70) compared with the Hadlock (AUC = 0.66) and FMF (AUC = 0.64) standards. Evaluation of partial AUC (FPR < 10%) demonstrated that the INTERGROWTH-21^st standard performed better than the Hadlock standard for the prediction of NICU admission and mechanical ventilation (P < 0.05 for both). Although fetuses with EFW > 90^th percentile were also at risk for any adverse perinatal outcome according to the INTERGROWTH-21^st (RR = 1.4; 95% CI, 1.0-1.9) and Hadlock (RR = 1.7; 95% CI, 1.1-2.6) standards, many times fewer cases (2-5-fold lower sensitivity) were detected by using EFW > 90^th percentile, rather than EFW < 10^th percentile, in screening by these standards.

CONCLUSIONS

Fetuses with EFW < 10^th percentile or EFW > 90^th percentile were at increased risk of adverse perinatal outcomes according to all or some of the eight growth standards, respectively. The RR of a composite adverse perinatal outcome in pregnancies with EFW < 10^th percentile was higher for the most-stringent (NICHD) compared with the least-stringent (FMF) standard. The results of the complementary analysis of AUC suggest slightly improved detection of adverse perinatal outcome by more recent population-based (INTERGROWTH-21^st ) and customized (PRB/NICHD) standards compared with the Hadlock and FMF standards. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

Customized fetal growth standard compared with the INTERGROWTH-21st century standard at predicting small-for-gestational-age neonates

INTRODUCTION

The INTERGROWTH-21st project (IG-21) was recently performed aiming to provide a universal benchmark for comparing fetal growth across different ethnicities. Our aim was to compare the IG-21 with a customized standard for predicting pregnancies at risk for neonatal small-for-gestational age (SGA) and adverse outcomes.

MATERIAL AND METHODS

This was a prospective cohort study including singleton pregnancies presenting for fetal growth assessment between 26 and 36 weeks of gestation. Fetal growth restriction was defined as estimated fetal weight <10th centile for gestational age using IG-21 and a customized standard. Neonatal SGA was defined as birthweight <10th centile for gestational age by the Alexander chart. Primary outcome was the prediction of neonatal SGA. Secondary outcomes included a composite of adverse neonatal outcomes. The discriminatory ability of each growth standard was compared using area under receiver operating characteristic curves (AUC).

RESULTS

Of 1054 pregnancies meeting the inclusion criteria, the incidence of neonatal SGA was 139 (13.2%), and a composite adverse neonatal outcome occurred in 300 (28.4%). The sensitivity of the customized standard (38.8%) was higher than that of IG-21 (24.5%) for predicting neonatal SGA, with AUC (95% CI) of 0.67 (0.63-0.71) for customized vs 0.62 (0.58-0.65) for IG-21; P = .003. Both standards were comparable in predicting the composite adverse neonatal outcomes: AUC (95% CI) 0.52 (0.50-0.55) for customized vs 0.51 (0.50-0.53) for IG-21; P = 0.25.

CONCLUSIONS

Both growth standards had modest performance in detecting neonatal SGA and were poor at predicting short-term adverse neonatal outcome.

Fetal Biometry and Doppler Study for the Assessment of Perinatal Outcome in Stage I Late-Onset Fetal Growth Restriction

OBJECTIVE

To compare perinatal outcomes on fetuses classified as stage I late-onset fetal growth restriction (FGR) depending on the estimated fetal weight (EFW) centile category and the fetal and maternal Doppler study.

MATERIAL AND METHODS

Retrospective cohort study on 131 cases of stage I late-onset FGR (diagnosis ≥32+0 weeks), defined as: EFW < 3rd centile and normal Doppler (G1) or EFW < 10th centile and mean uterine artery pulsatility index (PI) > 95th centile (G2) or EFW < 10th centile and mild fetal Doppler alteration: umbilical artery PI > 95th centile, middle cerebral artery PI < 5th centile, or cerebroplacental ratio < 5th centile (G3). All groups were compared to their perinatal results.

RESULTS

There were 37, 30, and 64 cases in G1, G2, and G3, respectively. G1 and G2 showed lower percentages of cesarean section when compared with G3 (18.4, 22.5, and 45.3% (p < 0.01), respectively), being attributable to an excess of cesarean sections for non-reassuring fetal status. These differences remained when definitive birth weight centile was above that considered to define FGR, being 5.9, 12.5, and 41.8% (p < 0.01), respectively.

DISCUSSION

In stage I late-onset FGR fetuses, abnormal fetal Doppler is associated with a poorer tolerance to vaginal delivery, even when the birth weight is > 10th centile.

Customized vs population-based growth charts to identify neonates at risk of adverse outcome: systematic review and Bayesian meta-analysis of observational studies

OBJECTIVE

To compare the effectiveness of customized vs population-based growth charts for the prediction of adverse pregnancy outcomes.

METHODS

MEDLINE, ClinicalTrials.gov and The Cochrane Library were searched up to 31 May 2016 to identify interventional and observational studies comparing adverse outcomes among large- (LGA) and small- (SGA) for-gestational-age neonates, when classified according to customized vs population-based growth charts. Perinatal mortality and admission to the neonatal intensive care unit (NICU) of both SGA and LGA neonates, intrauterine fetal demise (IUFD) and neonatal mortality of SGA neonates, and neonatal shoulder dystocia and hypoglycemia as well as maternal third- and fourth-degree perineal lacerations in LGA pregnancies were evaluated.

RESULTS

The electronic search identified 237 records that were examined based on title and abstract, of which 27 full-text articles were examined for eligibility. After excluding seven articles, 20 observational studies were included in a Bayesian meta-analysis. Neonates classified as SGA according to customized growth charts had higher risks of IUFD (odds ratio (OR), 7.8 (95% CI, 4.2-12.3)), neonatal death (OR, 3.5 (95% CI, 1.1-8.0)), perinatal death (OR, 5.8 (95% CI, 3.8-7.8)) and NICU admission (OR, 3.6 (95% CI, 2.0-5.5)) than did non-SGA cases. Neonates classified as SGA according to population-based growth charts also had increased risk for adverse outcomes, albeit the point estimates of the pooled ORs were smaller: IUFD (OR, 3.3 (95% CI, 1.9-5.0)), neonatal death (OR, 2.9 (95% CI, 1.2-4.5)), perinatal death (OR, 4.0 (95% CI, 2.8-5.1)) and NICU admission (OR, 2.4 (95% CI, 1.7-3.2)). For LGA vs non-LGA, there were no differences in pooled ORs for perinatal death, NICU admission, hypoglycemia and maternal third- and fourth-degree perineal lacerations when classified according to either the customized or the population-based approach. In contrast, both approaches indicated that LGA neonates are at increased risk for shoulder dystocia than are non-LGA ones (OR, 7.4 (95% CI, 4.9-9.8) using customized charts; OR, 8.0 (95% CI, 5.3-10.1) using population-based charts).

CONCLUSIONS

Both customized and population-based growth charts can identify SGA neonates at risk for adverse outcomes. Although the point estimates of the pooled ORs may differ for some outcomes, the overlapping CIs and lack of direct comparisons prevent conclusions from being drawn on the superiority of one method. Future clinical trials should compare directly the two approaches in the management of fetuses of abnormal size. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Predicting stillbirth in a low resource setting

Background

Stillbirth is a major contributor to perinatal mortality and it is particularly common in low- and middle-income countries, where annually about three million stillbirths occur in the third trimester. This study aims to develop a prediction model for early detection of pregnancies at high risk of stillbirth.

Methods

This retrospective cohort study examined 6,573 pregnant women who delivered at Federal Medical Centre Bida, a tertiary level of healthcare in Nigeria from January 2010 to December 2013. Descriptive statistics were performed and missing data imputed. Multivariable logistic regression was applied to examine the associations between selected candidate predictors and stillbirth. Discrimination and calibration were used to assess the model’s performance. The prediction model was validated internally and over-optimism was corrected.

Results

We developed a prediction model for stillbirth that comprised maternal comorbidity, place of residence, maternal occupation, parity, bleeding in pregnancy, and fetal presentation. As a secondary analysis, we extended the model by including fetal growth rate as a predictor, to examine how beneficial ultrasound parameters would be for the predictive performance of the model. After internal validation, both calibration and discriminative performance of both the basic and extended model were excellent (i.e. C-statistic basic model = 0.80 (95 % CI 0.78–0.83) and extended model = 0.82 (95 % CI 0.80–0.83)).

Conclusion

We developed a simple but informative prediction model for early detection of pregnancies with a high risk of stillbirth for early intervention in a low resource setting. Future research should focus on external validation of the performance of this promising model.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1061-2) contains supplementary material, which is available to authorized users.

Customized Fetal Growth Charts for Parents' Characteristics, Race, and Parity by Quantile Regression Analysis: A Cross-sectional Multicenter Italian Study

OBJECTIVES

The purpose of this study was to construct fetal biometric charts between 16 and 40 weeks' gestation that were customized for parental characteristics, race, and parity, using quantile regression analysis.

METHODS

In a multicenter cross-sectional study, 8070 sonographic examinations from low-risk pregnancies between 16 and 40 weeks' gestation were analyzed. The fetal measurements obtained were biparietal diameter, head circumference, abdominal circumference, and femur diaphysis length. Quantile regression was used to examine the impact of parental height and weight, parity, and race across biometric percentiles for the fetal measurements considered.

RESULTS

Paternal and maternal height were significant covariates for all of the measurements considered (P < .05). Maternal weight significantly influenced head circumference, abdominal circumference, and femur diaphysis length. Parity was significantly associated with biparietal diameter and head circumference. Central African race was associated with head circumference and femur diaphysis length, whereas North African race was only associated with femur diaphysis length.

CONCLUSIONS

In this study we constructed customized biometric growth charts using quantile regression in a large cohort of low-risk pregnancies. These charts offer the advantage of defining individualized normal ranges of fetal biometric parameters at each specific percentile corrected for parental height and weight, parity, and race. This study supports the importance of including these variables in routine sonographic screening for fetal growth abnormalities.

Diagnostic accuracy of placental growth factor and ultrasound parameters to predict the small-for-gestational-age infant in women presenting with reduced symphysis-fundus height

OBJECTIVES

To assess the diagnostic accuracy of placental growth factor (PlGF) and ultrasound parameters to predict delivery of a small-for-gestational-age (SGA) infant in women presenting with reduced symphysis-fundus height (SFH).

METHODS

This was a multicenter prospective observational study recruiting 601 women with a singleton pregnancy and reduced SFH between 24 and 37 weeks' gestation across 11 sites in the UK and Canada. Plasma PlGF concentration < 5(th) centile, estimated fetal weight (EFW) < 10(th) centile, umbilical artery Doppler pulsatility index > 95(th) centile and oligohydramnios (amniotic fluid index < 5 cm) were compared as predictors for a SGA infant < 3(rd) customized birth-weight centile and adverse perinatal outcome. Test performance statistics were calculated for all parameters in isolation and in combination.

RESULTS

Of the 601 women recruited, 592 were analyzed. For predicting delivery of SGA < 3(rd) centile (n = 78), EFW < 10(th) centile had 58% sensitivity (95% CI, 46-69%) and 93% negative predictive value (NPV) (95% CI, 90-95%), PlGF had 37% sensitivity (95% CI, 27-49%) and 90% NPV (95% CI, 87-93%); in combination, PlGF and EFW < 10(th) centile had 69% sensitivity (95% CI, 55-81%) and 93% NPV (95% CI, 89-96%). The equivalent receiver-operating characteristics (ROC) curve areas were 0.79 (95% CI, 0.74-0.84) for EFW < 10(th) centile, 0.70 (95% CI, 0.63-0.77) for low PlGF and 0.82 (95% CI, 0.77-0.86) in combination.

CONCLUSIONS

For women presenting with reduced SFH, ultrasound parameters had modest test performance for predicting delivery of SGA < 3(rd) centile. PlGF performed no better than EFW < 10(th) centile in determining delivery of a SGA infant.

Application of Customized Birth Weight Curves in the Assessment of Perinatal Outcomes in Infants of Diabetic Mothers

Objective: To determine whether the use of customized curves (CC) allows better detection of large- (LGA) or small-for-gestational age (SGA) infants at risk of adverse perinatal morbidity than non-CC in women with diabetes mellitus (DM). Material and Methods: A model of CC was applied to all infants of diabetic mothers (IDM) who attended the Hospital Universitario Materno Infantil de Canarias between 2008 and 2011. We compared perinatal outcomes of IDM classified as LGA or SGA by non-CC versus CC. Results: One of 4 LGA was appropriate for gestational age (AGA) by CC (false-positive rate: 25%) and 30% of SGA by CC were not identified by non-CC (false-negative rate). False-positive LGA and SGA showed similar perinatal outcomes to AGA infants. The rates of cesarean section, cephalopelvic disproportion, total fetal distress and shoulder dystocia were significantly higher in false-negative LGA than in AGA by CC (p < 0.004, p < 0.02, p < 0.04 and p < 0.04, respectively). Fetal distress was higher in false-negative SGA than in AGA by CC (p < 0.03). Discussion: In pregnancies complicated by DM, the use of CC allowed more accurate identification of LGA and SGA infants at high risk of perinatal morbidity than non-CC.

Customized growth curves for identification of large-for-gestational age neonates in pre-eclamptic women

OBJECTIVES

To compare the role of two nomograms to classify large-for-gestational age (LGA) neonates in women with pre-eclampsia and to determine the frequency of placental vascular lesions according to the timing of delivery.

METHOD

This cohort study included 118 consecutive women with pre-eclampsia delivering between 23 and 41 weeks’ gestation. The frequencies of LGA neonates according to customized growth curves and a national birth weight (BW) chart were compared. Similarly, the frequencies of LGA neonates and histological placental vascular lesions were compared between pre-eclamptic women delivering at <34 weeks (n=40) and those delivering later (n=78).

RESULTS

Customized growth curves allowed classification of a higher proportion of LGA neonates than did BW curves (18.6% (22/118) vs 10.2% (12/118); P=0.002). Among pre-eclamptic women delivering at ≥34 weeks, but not earlier, the proportion of neonates classified as LGA by customized growth curves was higher than that classified by BW curves (26.9% (21/78) vs 15.4% (12/78); P=0.004). Placental vascular lesions were less frequent in pre-eclamptic women delivering at ≥34 weeks than in those delivering earlier (41% (32/78) vs 62.5% (25/40); P=0.03).

CONCLUSIONS

Customized growth curves allow classification of a higher proportion of LGA neonates than do population birth weight curves among women with pre-eclampsia delivering at ≥34 weeks. Pre-eclamptic women delivering at ≥34 weeks have fewer placental vascular lesions than do those delivering earlier.

Effects of maternal obstructive sleep apnoea on fetal growth: a prospective cohort study

OBJECTIVE

The objective of this study is to determine whether obstructive sleep apnea (OSA) is associated with reduced fetal growth, and whether nocturnal oxygen desaturation precipitates acute fetal heart rate changes.

STUDY DESIGN

We performed a prospective observational study, screening 371 women in the second trimester for OSA symptoms. 41 subsequently underwent overnight sleep studies to diagnose OSA. Third trimester fetal growth was assessed using ultrasound. Fetal heart rate monitoring accompanied the sleep study. Cord blood was taken at delivery, to measure key regulators of fetal growth.

RESULTS

Of 371 women screened, 108 (29%) were high risk for OSA. 26 high risk and 15 low risk women completed the longitudinal study; 14 had confirmed OSA (cases), and 27 were controls. The median (interquartile range) respiratory disturbance index (number of apnoeas, hypopnoeas or respiratory related arousals/hour of sleep) was 7.9 (6.1-13.8) for cases and 2.2 (1.3-3.5) for controls (p<0.001). Impaired fetal growth was observed in 43% (6/14) of cases, vs 11% (3/27) of controls (RR 2.67; 1.25-5.7; p = 0.04). Using logistic regression, only OSA (OR 6; 1.2-29.7, p = 0.03) and body mass index (OR 2.52; 1.09-5.80, p = 0.03) were significantly associated with impaired fetal growth. After adjusting for body mass index on multivariate analysis, the association between OSA and impaired fetal growth was not appreciably altered (OR 5.3; 0.93-30.34, p = 0.06), although just failed to achieve statistical significance. Prolonged fetal heart rate decelerations accompanied nocturnal oxygen desaturation in one fetus, subsequently found to be severely growth restricted. Fetal growth regulators showed changes in the expected direction- with IGF-1 lower, and IGFBP-1 and IGFBP-2 higher- in the cord blood of infants of cases vs controls, although were not significantly different.

CONCLUSION

OSA may be associated with reduced fetal growth in late pregnancy. Further evaluation is warranted to establish whether OSA may be an important contributor to adverse perinatal outcome, including stillbirth.

Intrauterine growth restriction: effects of physiological fetal growth determinants on diagnosis

The growth of the fetus, which is strongly associated with the outcome of pregnancy, reflects interplay of several physiological and pathological factors. The assessment of fetal growth is based on comparison of birthweight (BW) or estimated fetal weight (EFW) to standards which define reference ranges at a spectrum of gestational ages. Most birthweight standards do not take into account effects of physiological determinants of fetal growth. Additionally, gestational age in many standards is based on the menstrual history and is often inaccurate. Fetal growth norms should be based on an early ultrasound estimate of gestational age. Customized standards, which have included only ultrasound-dated pregnancies, seem to be superior to population-based birthweight norms in predicting perinatal mortality and morbidity. Adjustment for individual variation in customized growth curves reduces false-positive diagnosis of IUGR and may lead to a very significant reduction in intervention for suspected IUGR. Customized growth potential identifies better the risk for adverse outcome than the currently used national standards, but customized charts may fail in detecting growth-restricted stillbirth. An individual's birthweight is the sum of physiological and pathological influences operating during pregnancy. Growth potential norms are a better discriminator of aberrations of fetal growth than population, ultrasound, and customized norms.

Customized growth charts for twin gestations to optimize identification of small-for-gestational age fetuses at risk of intrauterine fetal death

OBJECTIVE

Customized growth charts developed for singleton pregnancies have been shown to be more effective than population-based ones at identifying small-for-gestational age (SGA) fetuses at risk for intrauterine fetal death (IUFD). We sought to compare the association between SGA and IUFD in twins using customized growth charts designed for twin gestations compared to those designed for singletons.

METHODS

This was a retrospective cohort study using a database including singleton and twin pregnancies undergoing ultrasound examination between 16 and 20 weeks' gestation. After excluding preterm births < 34 weeks, congenital anomalies and stillbirths, we identified 51, 150 singleton births. Coefficients for significant physiological and pathological variables affecting birth weight for singletons were derived using backward stepwise multiple regression. The same process was repeated for twin births (1608 pairs), also adjusting for chorionicity. Customized growth charts for each pregnancy were derived using these two regression models for optimal birth weight at term and a proportionality equation. The association between SGA < 10(th) percentile, defined using the twin and singleton-customized charts, and IUFD were compared. Statistical analysis, including calculation of adjusted odds ratios (OR) for IUFD and screening accuracy using each chart, was performed.

RESULTS

The derived coefficients for optimal birth weight for twins were different from those for singletons, with lower constants and root mean square error (3422 and 288.9, respectively, in twins vs 3543 and 416 in singletons). Among 3786 twin infants, IUFD was seen in 123 (3.2%). The numbers of fetuses identified as SGA were 575 (15.2%) and 504 (13.3%) by the singleton and twin charts, respectively. Fetuses classified as SGA by the twin-specific customized charts were at a significantly increased risk for IUFD (adjusted OR, 2.3 (95% CI, 1.4-3.5)), whereas those classified as SGA by the singleton-customized charts were not (adjusted OR, 1.2 (95% CI, 0.7-2.0)).

CONCLUSION

Customized charts designed specifically for twins are more effective at identifying twin pregnancies at risk for IUFD than are those derived using singleton birth data.

Customized estimated fetal weight: a novel antenatal tool to diagnose abnormal fetal growth

OBJECTIVE

We sought to apply customized standards to ultrasound-derived estimated fetal weight (EFW), and assess the frequency of abnormal growth when compared to population-based standards. We also evaluated association with adverse perinatal outcomes.

STUDY DESIGN

This was a historical cohort using prenatal ultrasound examination data at ≥24 weeks over a 1-year period. Ultrasound-derived EFW and growth percentile (population-based EFW [popEFW]) were reported and compared to a customized EFW (custEFW).

RESULTS

In all, 782 women met inclusion criteria. More fetuses were identified as small for gestational age (SGA) (15.1% vs 3.8%; P < .0001) and large for gestational age (LGA) (6.8% vs 1.7%; P < .0001) using custEFW, and adverse perinatal outcomes were more frequent among those identified by the custEFW compared to the popEFW. Both SGA and LGA diagnosed by custEFW were predictive of a neonatal SGA (positive likelihood ratio, 8.64) and LGA (positive likelihood ratio, 15.4).

CONCLUSION

CustEFW was a better predictor of abnormal birthweight and adverse outcomes compared to traditional popEFW standards.