Application of ultrasonographic human estimated foetal weight formulas to cynomolgus monkeys (Macaca fascicularis) at 129-132 days of gestation: A comparative study of estimated and actual birthweight

BACKGROUND

Cynomolgus monkeys (Macaca fascicularis) are essential in biomedical research, including reproductive studies. However, the application of human estimated foetal weight (EFW) formulas using ultrasonography (USG) in these non-human primates is not well established.

OBJECTIVES

This study aims to evaluate the applicability of human EFW formulas for estimating foetal weight in cynomolgus monkeys at approximately 130 days of gestation.

METHODS

Our study involved nine pregnant cynomolgus monkeys. We measured foetal parameters, including biparietal diameter, head circumference, abdominal circumference and femur length using USG. The EFW was calculated using 11 human EFW formulas. The actual birthweight (ABW) was recorded following Cesarean section, the day after the EFW calculation. For comparing EFW and ABW, we employed statistical methods such as mean absolute percentage error (APE) and Bland-Altman analysis.

RESULTS

The ABW ranged between 200.36 and 291.33 g. Among the 11 formulas, the Combs formula showed the lowest APE (4.3%) and highest correlation with ABW (p < 0.001). Notably, EFW and ABW differences for the Combs formula were ≤5% in 66.7% and ≤10% in 100% of cases. The Bland-Altman analysis supported these results, showing that all cases fell within the limits of agreement.

CONCLUSIONS

The Combs formula is applicable for estimating the weight of cynomolgus monkey fetuses with USG at approximately 130 days of gestation. Our observations suggest that the Combs formula can be applied in the prenatal care and biomedical research of this species.

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.

Multimodal Early Birth Weight Prediction Using Multiple Kernel Learning

In this work, a novel multimodal learning approach for early prediction of birth weight is presented. Fetal weight is one of the most relevant indicators in the assessment of fetal health status. The aim is to predict early birth weight using multimodal maternal-fetal variables from the first trimester of gestation (Anthropometric data, as well as metrics obtained from Fetal Biometry, Doppler and Maternal Ultrasound). The proposed methodology starts with the optimal selection of a subset of multimodal features using an ensemble-based approach of feature selectors. Subsequently, the selected variables feed the nonparametric Multiple Kernel Learning regression algorithm. At this stage, a set of kernels is selected and weighted to maximize performance in birth weight prediction. The proposed methodology is validated and compared with other computational learning algorithms reported in the state of the art. The obtained results (absolute error of 234 g) suggest that the proposed methodology can be useful as a tool for the early evaluation and monitoring of fetal health status through indicators such as birth weight.

Fasting plasma glucose and fetal ultrasound predict the occurrence of neonatal macrosomia in gestational diabetes mellitus

OBJECTIVE

The cause of fetal overgrowth during pregnancy is still unclear. This study aimed to analyze and predict the risk of macrosomia in pregnant women with gestational diabetes mellitus (GDM).

METHODS

This study was a retrospective study collected from October 2020 to October 2021. A total of 6072 pregnant women with a routine 75-g oral glucose tolerance test (OGTT) during 24-28 gestational weeks were screened. Nearly equal numbers of pregnant women with gestational diabetes and with normal glucose tolerance (NGT) were included in the study. Multivariate logistic regression analysis and receiver operating characteristic (ROC) curve were performed to determine the index and inflection point for predicting macrosomia occurrence.

RESULTS

The data of perinatal outcomes of 322 GDM and 353 NGT who had given birth to single live babies at term were analyzed. We found that significant cut-off values for the prediction of macrosomia are 5.13mmol/L in fasting plasma glucose (FPG), 12.25kg in gestational weight gain (GWG), 3,605g in ultrasound fetal weight gain (FWG) and 124mm in amniotic fluid index (AFI).The area under the ROC curve of this predictive model combined all variables reached 0.953 (95% CI: 0.914 ~ 0.993) with a sensitivity of 95.0% and a specificity of 85.4%.

CONCLUSIONS

FPG is positively associated with newborn birth weight. An early intervention to prevent macrosomia may be possible by combining maternal GWG, FPG, FWG, and AFI in gestational diabetes.

Accuracy and precision of sonographic fetal weight estimation in Sweden

INTRODUCTION

Fetal growth assessment by ultrasound is an essential part of modern obstetric care. The formula by Persson and Weldner for estimated fetal weight (EFW), used in Sweden since decades, has not yet been evaluated. The objective of this study was to evaluate accuracy and precision of the formula by Persson and Weldner, and to compare it to two other formulae using biparietal diameter instead of head circumference.

MATERIAL AND METHODS

The study population consisted of 31 521 singleton pregnancies delivered at 22⁺⁰ gestational weeks or later, with an ultrasound EFW performed within 2 days before delivery, registered in the Swedish Pregnancy Register between 2014 and 2021. Fetal biometric ultrasound measurements were used to calculate EFW according to the formulae by Persson and Weldner, Hadlock 2 and Shepard. Bland-Altman analysis, systematic error (mean percentage error), random error (standard deviation [SD] of mean percentage error), proportion of weight estimates within ±10% of birthweight, and proportion with underestimated and overestimated weight was calculated. Moreover, calculations were made after stratification into small, appropriate, and large for gestational age (SGA, AGA and LGA), respectively, and gestational age at examination.

RESULTS

For the formula by Persson and Weldner, MPE was -2.7 (SD 8.9) and the proportion of EFW within ±10% from actual birthweight was 76.0%. MPE was largest for fetuses estimated as severe SGA (<3rd percentile, -5.4) and for the most preterm fetuses (<24 weeks, -5.4). For Hadlock 2 and Shepard's formulae, MPE were 3.9 (SD 8.9) and 3.4 (SD 9.7), respectively, and the proportions of EFW within ±10% from actual birthweight were 69.4% and 67.1%, respectively. MPE was largest for fetuses estimated as severe LGA (>97th percentile), 7.6 and 9.4, respectively.

CONCLUSIONS

The recommended Swedish formula by Persson and Weldner is generally accurate for fetal weight estimation. The systematic underestimation of EFW and random error is largest in extreme preterm and estimated SGA-fetuses, which is of importance in clinical decision making. The accuracy of EFW with the formula by Persson and Weldner is as good as or better than Hadlock 2 and Shepard's formulae.

Accuracy of Fetal Biacromial Diameter and Derived Ultrasonographic Parameters to Predict Shoulder Dystocia: A Prospective Observational Study

Background and Objectives: Shoulder dystocia (ShD) is one of most dangerous obstetric complication. The objective of this study was to determine if the ultrasonographic fetal biacromial diameter (BA) and derived parameters could predict ShD in uncomplicated term pregnancies. Materials and Methods: We conducted a prospective observational study in a tertiary care university hospital from March 2021 to February 2022. We included all full-term pregnancies accepted for delivery that received an accurate ultrasonography (USG) scan before delivery. USG biometry and estimated fetal weight (EFW) were collected. Therefore, we evaluated the diameter of the mid-arm, the transverse thoracic diameter (TTD) and the biacromial diameter (BA). BA was estimated using Youssef’s formula: TTD + 2 mid-arm diameters. The primary outcome was the evaluation of BA and its related parameters (BA/biparietal diameter (BPD), BA/head circumference (HC) and BA–BPD in fetuses with ShD versus fetuses without ShD. Diagnostic accuracy for ShD of BA, BA/BPD, BA/HC and BA–BPD was evaluated using receiver operator curve (ROC) analysis. Results: 90 women were included in the analysis, four of these had ShD and required extra maneuvers after head delivery. BA was increased in fetuses with ShD (150.4 cm; 95% CI 133.2 cm to 167.6 cm) compared to no-ShD (133.5 cm; 95% CI 130.1 cm to 137.0 cm; p = 0.04). Significant differences were also found between ShD and no-ShD groups for BA/BPD (1.66 (95% CI 1.46 to 1.86) vs. 1.44 (95% CI 1.41 to 1.48); p = 0.04), BA/HC (0.45 (95% CI 0.40 to 0.49) vs. 0.39 (95% CI 0.38 to 0.40); p = 0.01), BA–BPD (60.0 mm (95% CI 42.4 to 77.6 cm) vs. 41.4 (95% CI 38.2 to 44.6); p = 0.03), respectively. ROC analysis showed an overall good accuracy for ShD, with an AUC of 0.821 (p = 0.001) for BA alone and 0.881 (p = 0.001), 0.857 (p = 0.016) and 0.867 (p = 0.013) for BA/BPD, BA–BPD and BA/HC, respectively. Conclusions: BA alone, as well as BA/BPD, BA/HC and BA–BPD might be useful predictors of ShD in uncomplicated term pregnancies. However, such evidence needs extensive confirmation by means of additional studies with large sample sizes, especially in case of pregnancies at high risk for ShD (i.e., gestational diabetes).

Fetal growth restriction with abnormal individual biometric parameters at second trimester ultrasound is associated with small for gestational age neonate at delivery

OBJECTIVES

To determine if early-onset fetal growth restriction with abnormal individual biometric parameters, defined as head circumference, abdominal circumference and femur length less than the 10th percentile, is associated with adverse neonatal outcomes compared to fetal growth restriction with normal biometric parameters.

STUDY DESIGN

Retrospective cohort study including women diagnosed with fetal growth restriction between 16 and 24 weeks gestation who delivered a singleton, non-anomalous neonate at Mount Sinai Hospital from 2013 to 2019. The primary outcome was rate of small for gestational age neonate at delivery. Maternal, obstetric and neonatal outcomes were compared using multivariable regression analysis.

RESULTS

Patients diagnosed with fetal growth restriction with abnormal biometric parameters were more likely to be nulliparous, diagnosed with severe growth restriction and to receive antenatal corticosteroids than those with normal biometric parameters. The rate of small for gestational age neonate at delivery was higher in those with abnormal parameters (OR 4.0, 95% CI 1.7-9.2, p < 0.01) when compared to normal parameters. The rate of resolution of fetal growth restriction was higher in the normal biometric parameter group compared to those with abnormal parameters (OR 3.3, 95% CI 1.4-8.1, p < 0.01).

CONCLUSIONS

Fetal growth restriction and normal biometric parameters diagnosed at second trimester ultrasound is associated with an increased likelihood of resolution of growth restriction and decreased likelihood of delivering a small for gestational age neonate.

Antenatal prediction of fetal macrosomia in pregnancies affected by maternal pre-gestational diabetes

AIMS

Higher rates of fetal macrosomia may occur in infants of women with pre-gestational diabetes compared with non-diabetic controls. Antenatal predication of fetal macrosomia remains challenging. Ultrasound over-estimated fetal weight could result in over-classification of fetuses as macrosomic with corresponding inappropriate clinical interventions. Previously we had studied a measurement - the anterior abdominal wall measurement (AAW) - to predict fetal macrosomia in fetal estimation of weight. The purpose of the study was to study whether specific third trimester ultrasound measurements with measures of glycaemic control (HbA1c) predicted macrosomia in babies born to women with pre-gestational diabetes. In particular, a new variant of this measurement (fetal anterior abdominal wall thickness (AAW), abdominal circumference (AC) ratio: AAW:AC) was investigated.

METHODS

This was a prospective cohort study in a tertiary referral maternity hospital. Serial growth scans including measurement of AAW and AC: AAW ratio was performed at 30, 33- and 36-weeks' gestation. Birth-weight data was collected, and macrosomia was defined as >90th centile based on gestational age and gender of the baby. Serial HbA1c as measured at the first antenatal visit, 14, 20- and 36-weeks' gestation were reported for this study.

RESULTS

Of the 416 pregnancies analyzed, mean maternal age was 33.3 years. One in five women were primigravida's. The mean birthweight was 3548 g (+/- 581 g), of which 142 (34%) babies were classified as macrosomic. The median gestational age at delivery was 38³ weeks (31⁴ - 40² weeks). There were 37 (9%) babies born preterm at <37 weeks' gestation. Mean AC measurements in fetuses that would be born with macrosomia compared with those with a non-macrosomic birth weight were 282 mm vs. 266 mm at 30 weeks, 318.3 mm vs. 297 mm at 33 weeks and 350 mm vs. 325 mm at 36 weeks' gestation (all p < .001). Mean AAW measurements in macrosomic fetuses compared with normal size fetuses were 3.7 mm vs. 3.3 mm at 30 weeks, 4.9 mm vs 4.3 mm at 33 weeks and 5.9 mm vs. 5.3 mm at 36 weeks' gestation (all p < .001). The mean AC: AAW was 0.01 for both normal and macrosomic fetuses at 30 weeks. There was no clinical or statistical difference in AC:AAW ratios between non-macrosomic and macrosomic infants. Binary logistic regression showed that AC at 36 weeks was most predictive of macrosomia (76.5%), followed by AAW at 30 weeks (68.5%). Using a combination of HbA1c booking, 14, 20, 36 weeks and AAW 30, 33, 36 weeks and AC 30, 33, 36 weeks predicted macrosomia in 80.9%. The ratio of AC: AAW did not act as a useful antenatal clinical predictor of macrosomia at birth.

CONCLUSIONS

Abdominal circumference at 36 weeks was the single best predictor of fetal macrosomia. A combined model of HbA1c, AC and AAW was the best antenatal predictor of macrosomia, with intriguing clinical possibilities in the possible prevention of maternal and fetal complications of macrosomia.

Swedish intrauterine growth reference ranges for estimated fetal weight

Fetal growth restriction is a strong risk factor for perinatal morbidity and mortality. Reliable standards are indispensable, both to assess fetal growth and to evaluate birthweight and early postnatal growth in infants born preterm. The aim of this study was to create updated Swedish reference ranges for estimated fetal weight (EFW) from gestational week 12-42. This prospective longitudinal multicentre study included 583 women without known conditions causing aberrant fetal growth. Each woman was assigned a randomly selected protocol of five ultrasound scans from gestational week 12 + 3 to 41 + 6. Hadlock's 3rd formula was used to estimate fetal weight. A two-level hierarchical regression model was employed to calculate the expected median and variance, expressed in standard deviations and percentiles, for EFW. EFW was higher for males than females. The reference ranges were compared with the presently used Swedish, and international reference ranges. Our reference ranges had higher EFW than the presently used Swedish reference ranges from gestational week 33, and higher median, 2.5th and 97.5th percentiles from gestational week 24 compared with INTERGROWTH-21st. The new reference ranges can be used both for assessment of intrauterine fetal weight and growth, and early postnatal growth in children born preterm.

Correlation of Fractional Limb Volume Measurements with Neonatal Morphometric Indices

OBJECTIVES

Fractional thigh volume (TVol) and fractional arm volume (AVol) measurements by three-dimensional (3D) ultrasound can reveal valuable information on fetal soft tissue development. However, it is not clear whether TVol or AVol provides better estimates of fetal body proportion and adiposity, independent of routine two-dimensional (2D) ultrasound biometry. The primary objective of the current study was to determine the correlations between fractional limb volumes (FLVs) and neonatal anthropometric parameters.

DESIGN

In this cross-sectional study, fetal FLVs were obtained within 24 h before term delivery from 40 medically and obstetrically uncomplicated pregnancies scheduled for elective cesarean section. TVol and AVol were determined using offline software. Postnatal morphometric data including birth weight; crown-heel, arm, and leg lengths; head, abdominal, mid-thigh, and mid-arm circumferences; and anterior thigh, biceps, and subscapular skinfold thicknesses were obtained. Pearson and partial correlation analyses were used to determine the relationships across antenatal volume calculations and neonatal indices. Correlation coefficients (r) were calculated.

RESULTS

Mean maternal age, BMI, and parity were 29.1 ± 5.4 years, 29.7 ± 3.5 kg/m2, and 1.0 ± 1.3, respectively. AVol showed moderate correlations with most of the neonatal parameters, including mid-thigh circumference (r = 0.683), mid-arm circumference (r = 0.627), birth weight (r = 0.583), head circumference (HC, r = 0.560), and abdominal circumference (r = 0.542). However, TVol was weakly related to only some of the indices. After controlling for gestational age, maternal age, BMI, parity, and 2D ultrasound biometry, TVol was no longer associated with any of the parameters, while AVol was independently correlated with mid-thigh (r = 0.724) and mid-arm circumference (r = 0.560), birth weight (r = 0.502), ponderal index (r = 0.402), HC (r = 0.382), biceps (r = 0.384), and subscapular skinfold thickness (r = 0.350).

LIMITATIONS

The current design includes limited number of pregnancies with only scheduled cesarean deliveries. Neonatal percent body fat was not calculated, and air-displacement plethysmography was not used to assess neonatal body composition. The study population was Caucasian with a relatively high maternal BMI, which may limit extrapolation of the results to other settings.

CONCLUSIONS

AVoL measurements by 3D ultrasound before delivery are significantly correlated with most of the neonatal morphometric indices, independent of maternal characteristics and 2D biometric parameters. AVol may have advantages over TVol for assessing limb soft tissue development in term fetuses. Future research can focus on feasibility and predictive ability of AVol measurements in prospective studies that include serial biometry over time.

Prenatal identification of small-for-gestational age and risk of neonatal morbidity and stillbirth

OBJECTIVE

To assess whether prenatal identification of small-for-gestational age (SGA) was associated with lower rates of the primary composite outcome of stillbirth, death in the delivery room or neonatal complications, and secondary outcomes of the composite outcome according to gestational age at delivery, stillbirth and low 5-min Apgar score.

METHODS

This historical cohort study included women who had a singleton delivery (≥ 32 weeks) between 1994 and 2011 at one of 247 French maternity units. We excluded pregnancies terminated medically, infants with malformations or with missing data on estimated fetal weight or birth weight, and women with missing delivery data. Among the 24 946 infants born SGA (< 5^th percentile), we compared those who had been identified as such prenatally (n = 5093; 20%), with those who had not (n = 19 853; 80%). The main outcome was a composite variable defined as stillbirth or death in the delivery room, or transfer to a neonatal department either immediately or during the neonatal stay in the obstetrics ward. Secondary outcomes were the composite outcome according to gestational age at delivery (32 to < 35 weeks; 35 to < 37 weeks, 37 to < 40 weeks, or ≥ 40 weeks), stillbirth and low 5-min Apgar score (≤ 4 and < 7).

RESULTS

The mean ± SD birth weight was 2449.1 ± 368.3 g. The rate of the main composite outcome was higher in the group identified prenatally as SGA compared with non-identified SGA fetuses (39.5% vs 13.5%; adjusted relative risk (aRR), 1.29; 95% CI, 1.21-1.38). This association was not observed in the subgroups delivered before 37 weeks. The stillbirth rate was lower in fetuses with prenatal suspicion of SGA (aRR, 0.47; 95% CI, 0.27-0.79), while the 5-min Apgar score did not differ between the two groups. The a-posteriori study power with α = 0.05 was 99%.

CONCLUSION

Prenatal identification of SGA was not associated with lower fetal or neonatal morbidity overall, although it was associated with a lower rate of stillbirth. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

The Accuracy of 22 Fetal Weight Estimation Formulas in Diabetic Pregnancies

PURPOSE

The objective of this study was to estimate the accuracy of 22 fetal weight estimation formulas in diabetic pregnancies uncomplicated and complicated by fetal macrosomia.

METHODS

Retrospectively collected data of 317 pregnancies complicated by gestational diabetes mellitus and 78 cases of fetal macrosomia were used in this study. Study inclusion criteria were women diagnosed with gestational diabetes mellitus, full-term singleton pregnancy, and an interval from the ultrasound to delivery of ≤7 days. The estimated fetal weight was calculated using 22 formulas. The mean absolute percentage error (MAPE) and two-way random interclass correlation coefficient were chosen for statistical analysis.

RESULTS

In the group of gestational diabetes, MAPE ranged from 8.43 ± 10.17 to 54.01 ± 9.50%. Most of the formulas showed a tendency to estimate a lower fetal weight in comparison to the actual birth weight. In the group of fetal macrosomia, the correlations were poor. Only three formulas reached the threshold of MAPE <10%.

CONCLUSIONS

The formula by Hsieh might be considered the best for fetal weight estimation in diabetic pregnancies. The combination of the best formulas might improve the accuracy of estimation. None of the formulas were accurate enough to predict fetal macrosomia.

Comparison of the accuracy of INTERGROWTH-21 formula with other ultrasound formulae in fetal weight estimation

OBJECTIVE

A new ultrasound formula for fetal weight estimation was proposed from the INTERGROWTH-21 project in 2017. There is no comparison of its accuracy with other ultrasound formulae. This study aims to compare the accuracy of INTERGROWTH-21 formula in fetal weight estimation with the traditional Hadlock1 and Shepard formula.

MATERIALS AND METHODS

All pregnant patients who had delivery in United Christian Hospital between January to December 2016 were retrospectively reviewed. Those who had prenatal ultrasound scan performed within 7 days of delivery were recruited. Hadlock1, Shepard and INTERGROWTH-21 formula were used to estimate the fetal weight and their accuracies were compared with the actual birthweight of neonates.

RESULTS

A total of 403 patients were recruited. Hadlock1 was the most accurate with the lowest mean absolute percentage error (MAPE) 7.34 when compared with Shepard (9.00; p < 0.001) and INTERGROWTH-21 (9.07; p < 0.001). INTERGROWTH-21 had the lowest proportion of patients having estimated fetal weight within 10% discrepancy from the actual birthweight (57.6%) compared with Hadlock1 (71.2%; p < 0.001) and Shepard (66.3; p = 0.011). Presence of intrauterine growth restriction (IUGR) or fetal macrosomia (>=4000 g) were both associated with significantly higher MAPE in Hadlock1 and INTERGROWTH-21. IUGR (p = 0.005) and macrosomia (p = 0.004) remained significant in the final equation of logistic regression model that affect the precision of fetal weight estimation in Hadlock1, while only IUGR was significant in INTERGROWTH-21 (p < 0.001).

CONCLUSION

INTERGROWTH-21 formula was not shown to be better than the traditional Hadlock1 or Shepard formulae. Future prospective studies would be required to evaluate the accuracy of INTERGROWTH-21 formula especially at the extremes of birthweight.

The Hadlock Method Is Superior to Newer Methods for the Prediction of the Birth Weight Percentile

OBJECTIVES

To compare a traditional ultrasound (US) method for estimated fetal weight (EFW) calculation and fetal growth restriction diagnosis with 2 newer methods for the prediction of small for gestational age (SGA) at birth.

METHODS

We reviewed deliveries at our institution from January 1, 2013, to March 31, 2017. Singleton, nonanomalous, well-dated fetuses with a US examination within 2 weeks of delivery were included. Estimated fetal weights and percentiles were calculated by a traditional method (Hadlock et al; Radiology 1991; 181:129-133) and 2 newer methods: Intergrowth-21st (INTG; Ultrasound Obstet Gynecol 2017; 49:478-486) and Salomon et al (Ultrasound Obstet Gynecol 2007; 29:550-555). We calculated each method's test characteristics to predict SGA (birth weight < 10th percentile) using both traditional (EFW < 10th percentile) and receiver operating characteristic (ROC)-derived fetal growth restriction cutoffs. Mean percentile discrepancies between EFW and birth weight measurements were calculated to compare method accuracy. We hypothesized that the INTG and Salomon methods would have superior SGA prediction compared with the Hadlock method.

RESULTS

Of 831 pregnancies with a US examination within 2 weeks of delivery, 138 (16.7%) were SGA at birth. Hadlock had the smallest US-birth weight percentile discrepancy (P < .001 versus both INTG and Salomon). When comparing ROC curves, the Hadlock and INTG methods performed comparably, with areas under the curve of 0.91 and 0.90 (P = .08) and optimal EFW cutoffs of the 15th and 22nd percentiles, respectively. The Salomon method performed less well, with an area under the curve of 0.82 (P < .001 versus both Hadlock and INTG methods).

CONCLUSIONS

In our study cohort, the Hadlock method predicted the birth weight percentile more accurately than the INTG or Salomon methods and performed comparably with INTG to predict SGA when ROC-derived cutoffs were used.

The value of ultrasound in predicting isolated inter-twin discordance and adverse perinatal outcomes

PURPOSE

To investigate the value of ultrasound approaching delivery to predict isolated inter-twin discordance and adverse perinatal outcomes.

METHODS

We retrospectively included twin pregnancies with sonography approaching delivery in ten maternal-foetal medicine centres in China from 2013 to 2014. Estimated foetal weight (EFW) and inter-twin EFW disparity (EFWD) were calculated based on biometry parameters. Percentage errors between EFW and actual birthweight or between EFWD and actual inter-twin disparity were calculated. ROC curves and multiple logistic regression were applied to evaluate the ability of EFWD to predict inter-twin disparity ≥ 25%, stillbirth, asphyxia and admission to a neonatal intensive unit (NICU). Chorionicity-stratified analysis was further performed.

RESULTS

Two hundred sixty-six monochorionic and 760 dichorionic twin pregnancies were analysed. The percentage errors in foetal weight estimations were 7-13%, whereas percentage errors in the estimation of inter-twin disparity were nearly 100%. Among eight formulas, Hadlock1 performed best, with a detectable rate of 65% and a false positive rate of 5% when predicting inter-twin disparity ≥ 25%. EFWD ≥ 22% was strongly associated with stillbirth (OR = 4.17, 95% CI 1.40-12.40) and NICU admission (OR = 3.48, 95% CI 2.03-5.97) after adjustment for gestational age, parity and abnormal umbilical systolic/diastolic ratio. Ultrasound had better predictive ability in monochorionic twins.

CONCLUSION

The predictive value of ultrasound for isolated inter-twin discordance and adverse perinatal outcomes was limited, which was possibly due to the magnifying of systematic errors in the disparity estimation compared with weight estimation. Despite this, abnormal biometry was an independent contributor for the poor prognosis of neonates.

Comparison of the Hadlock and INTERGROWTH formulas for calculating estimated fetal weight in a preterm population in France

BACKGROUND

Accurate estimation of fetal weight is needed for growth monitoring and decision-making in obstetrics; the INTERGROWTH project developed an estimated fetal weight formula to construct new intrauterine growth standards.

OBJECTIVE

We sought to compare the accuracy of the Hadlock and INTERGROWTH formulas for the estimation of fetal weight among preterm infants.

STUDY DESIGN

Using the EPIPAGE 2 population-based study of births between 22-34 weeks of gestation, we included 578 nonanomalous singleton fetuses with an ultrasound-to-delivery interval <2 days. We used abdominal circumference, head circumference, and femur length to calculate estimated fetal weight with Hadlock formula and abdominal and head circumferences to calculate estimated fetal weight according to INTERGROWTH. The mean percentage errors and the proportions of estimated fetal weight measures within ±10% of birthweight were compared between the 2 methods.

RESULTS

Mean (SD) gestational age and birthweight were 29.1 (SD 2.7) weeks and 1219 (SD 489) g. Mean (SD) percentage errors for Hadlock and INTERGROWTH were significantly different: -0.7 (SD 10.1) and -3.5 (SD 11.6), respectively (P < .001), and more infants were classified within ±10% of their birthweight with Hadlock compared to INTERGROWTH (68.7% vs 57.8%, P < .001). The INTERGROWTH formula overestimated birthweight at 22-23 weeks compared to Hadlock [mean errors of 18.8 (SD 13.6) vs 5.5 (SD 10.2)] and underestimated birthweight >28 weeks: at 29-31 weeks, mean errors were -5.8 (SD 10.9) for INTERGROWTH and -0.6 (SD 10.4) for Hadlock.

CONCLUSION

Hadlock estimated fetal weight formula was more accurate than INTERGROWTH formula for fetuses delivered between 22-34 weeks of gestation. Our results support continued use of Hadlock formula in France and raise questions about the applicability of INTERGROWTH intrauterine growth standards.

Ultrasonographic estimation of fetal weight: development of new model and assessment of performance of previous models

OBJECTIVES

To develop a new formula for ultrasonographic estimation of fetal weight and evaluate the accuracy of this and all previous formulae in the prediction of birth weight.

METHODS

The study population consisted of 5163 singleton pregnancies with fetal biometry at 22-43 weeks' gestation and live birth of a phenotypically normal neonate within 2 days of the ultrasound examination. Multivariable fractional polynomial analysis was used to determine the combination of variables that provided the best-fitting models for estimated fetal weight (EFW). A systematic review was also carried out of articles reporting formulae for EFW and comparing EFW to actual birth weight. The accuracy of each model for EFW was assessed by comparing mean percentage error, absolute mean error (AE), proportion of pregnancies with AE ≤ 10% and Euclidean distance.

RESULTS

The most accurate models, with the lowest Euclidean distance and highest proportion of AE ≤ 10%, were provided by the formulae incorporating ≥ 3 rather than < 3 biometrical measurements. The systematic review identified 45 studies describing a total of 70 models for EFW by various combinations of measurements of fetal head circumference (HC), biparietal diameter, femur length (FL) and abdominal circumference (AC). The most accurate model with the lowest Euclidean distance and highest proportion of AE ≤ 10% was provided by the formula of Hadlock et al., published in 1985, which incorporated measurements of HC, AC and FL; there was a highly significant linear association between EFW and birth weight (r = 0.959; P < 0.0001), and EFW was within 10% of birth weight in 80% of cases. The performance of the best model developed in this study, utilizing HC, AC and FL, was very similar to that of Hadlock et al. CONCLUSION: Despite many efforts to develop new models for EFW, the one reported in 1985 by Hadlock et al., from measurements of HC, AC and FL, provides the most accurate prediction of birth weight and can be used for assessment of all babies, including those suspected to be either small or large. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Early Second-Trimester Fetal Growth Restriction and Adverse Perinatal Outcomes

OBJECTIVE

To estimate the risk of adverse perinatal outcomes among women with isolated fetal growth restriction from 17 to 22 weeks of gestation.

METHODS

This was a retrospective cohort study of all singleton, nonanomalous pregnancies undergoing ultrasonography to assess fetal anatomy between 17 and 22 weeks of gestation at a single center from 2010 to 2014. After excluding patients with fetal structural malformations, chromosomal abnormalities, or identified infectious etiologies, we compared perinatal outcomes between pregnancies with and without fetal growth restriction, defined as estimated fetal weight less than the 10th percentile for gestational age. Our primary outcome was small for gestational age (SGA) at birth, defined as birth weight less than the 10th percentile. Secondary outcomes included preterm delivery at less than 37 and less than 28 weeks of gestation, preeclampsia, abruption, stillbirth, neonatal death, neonatal intensive care unit admission, intraventricular hemorrhage, need for respiratory support, and necrotizing enterocolitis.

RESULTS

Of 12,783 eligible patients, 355 (2.8%) had early second-trimester fetal growth restriction. Risk factors for growth restriction were African American race and tobacco use. Early second-trimester growth restriction was associated with a more than fivefold increase in risk of SGA at birth (36.9% compared with 9.1%, adjusted odds ratio [OR] 5.5, 95% CI 4.3-7.0), stillbirth (2.5% compared with 0.4%, OR 6.2, 95% CI 2.7-12.8), and neonatal death (1.4% compared with 0.3%, OR 5.2, 95% CI 1.6-13.5). Rates of indicated preterm birth at less than 37 weeks of gestation (7.3% compared with 3.3%, OR 2.3, 95% CI 1.5-3.5) and less than 28 weeks of gestation (2.5% compared with 0.2%, OR 10.8, 95% CI 4.5-23.4), neonatal need for respiratory support (16.9% compared with 7.8%, adjusted OR 1.6, 95% CI 1.1-2.2), and necrotizing enterocolitis (1.4% compared with 0.2%, OR 7.7, 95% CI 2.3-20.9) were also significantly higher for those with growth restriction. Rates of preeclampsia, abruption, and other neonatal outcomes were not significantly different.

CONCLUSION

Although fetal growth restriction in the early second trimester occurred in less than 3% of our cohort and most of those with isolated growth restriction did not have adverse outcomes, it is a strong risk factor for SGA, stillbirth, neonatal death, and indicated preterm birth.

Measurement and evaluation of fetal fat layer in the prediction of fetal macrosomia in pregnancies complicated by gestational diabetes

OBJECTIVES

To explore the predictive power of measuring the abdominal fetal fat layer (FFL) as a soft tissue marker at 31, 34, and 37 weeks' gestation to improve the detection of fetal macrosomia in pregnant women with GDM, in addition to the biometric values with close monitoring of maternal blood sugar level and BMI changes.

METHODS

We conducted a prospective observational study at the Department of Obstetrics, University Hospitals, Campus Kiel, Germany, in collaboration with diabetic clinic staff. Participants underwent a third-trimester scan and extra FFL measurements were performed at 31, 34, and 37 weeks of gestation. The clinical outcomes of pregnancy and birth weight were collected from the obstetric record. All of the enrolled women had an early pregnancy ultrasound scan to confirm gestational age.

RESULTS

The FFL at 34 and 37 weeks, with respective cutoff values of >0.48 cm and >0.59 cm, showed a very good sensitivity of 60% for both gestational points, and specificity of 89.3 and 90.6%, respectively. The probability of fetal macrosomia could be more than doubled if the FFL at 34 weeks was more than 0.48 cm. However, the probability of macrosomia dropped to 16% if the FFL was ≤0.48 cm. The median FFLs of macrosomic fetuses at 34 and 37 weeks were 0.50 (IQR 0.10) and 0.60 (IQR 0.25) cm, respectively. The mean age of the study population (n = 80) was 32.26 (SD = 5.06) years. In our study population, ten newborns were born with birth weight >4000 g. The body mass index (BMI) for the mothers of later-onset macrosomic newborns showed higher median values of 30 (IQR 8), 32 (IQR 5), and 33 (IQR 9) at 31, 34, and 37 weeks, respectively, in comparison to mothers of non-macrosomic newborn. However, the BMI did not show any statistically significant difference from those with normal-weight newborn and did not show any specific sensitivity for predicting macrosomia.

CONCLUSION

Measuring the FFL at 34 and 37 weeks of gestation, in addition to the standard measurement, might be useful for predicting macrosomia and is worth further evaluation.