Sonographic EFW and macrosomia: is there an optimum formula to predict diabetic fetal macrosomia?

The NICHD Fetal 3D Study: A Pregnancy Cohort Study of Fetal Body Composition and Volumes

There's a paucity of robust normal fractional limb and organ volume standards from a large and diverse ethnic population. The Fetal 3D Study was designed to develop research and clinical applications for fetal soft tissue and organ volume assessment. The NICHD Fetal Growth Studies (2009-2013) collected 2D and 3D fetal volumes. In the Fetal 3D Study (2015-2019), sonographers performed longitudinal 2D and 3D measurements for specific fetal anatomical structures in research ultrasounds of singletons and dichorionic twins. The primary aim was to establish standards for fetal body composition and organ volumes, overall and by maternal race/ethnicity, and determine whether these standards vary for twins versus singletons. We describe the study design, methods, and details about reviewer training. Basic characteristics of this cohort, with their corresponding distributions of fetal 3D measurements by anatomical structure, are summarized. This investigation is responsive to critical data gaps in understanding serial changes in fetal subcutaneous fat, lean body mass, and organ volume in association with pregnancy complications. In the future, this cohort can answer critical questions regarding the potential influence of maternal characteristics, lifestyle factors, nutrition, and biomarker and chemical data on longitudinal measures of fetal subcutaneous fat, lean body mass, and organ volumes.

Incidence of shoulder dystocia and risk factors for recurrence in the subsequent pregnancy-A historical register-based cohort study

INTRODUCTION

Shoulder dystocia is a rare obstetric complication, and the risk of recurrence is important for planning future deliveries.

MATERIAL AND METHODS

The objectives of our study were to estimate the incidence and risk factors for recurrence of shoulder dystocia and to identify women at high risk of recurrence in a subsequent vaginal delivery. The study design was a nationwide register-based study including data from the Danish Medical Birth Registry and National Patient Register in the period 2007-2017. Nulliparous women with a singleton fetus in cephalic presentation were included for analysis of risk factors in index and subsequent delivery.

RESULTS

During the study period, 6002 cases of shoulder dystocia were reported with an overall incidence among women with vaginal delivery of 1.2%. Among 222 225 nulliparous women with vaginal births, shoulder dystocia complicated 2209 (1.0%) deliveries. A subsequent birth was registered in 1106 (50.1%) of the women with shoulder dystocia in index delivery of which 837 (77.8%) delivered vaginally. Recurrence of shoulder dystocia was reported in 60 (7.2%) with a six-fold increased risk compared with women without a prior history of shoulder dystocia (risk ratio [RR] 5.70, 95% confidence interval [CI]: 4.41 to 7.38; adjusted RR 3.06, 95% CI: 2.03 to 4.68). Low maternal height was a significant risk factor for recurrence of shoulder dystocia. In the subsequent delivery, significant risk factors for recurrence were birthweight >4000 g, positive fetal weight difference exceeding 250 g from index to subsequent delivery, stimulation with oxytocin and operative vaginal delivery. In the subsequent pregnancy following shoulder dystocia, women who underwent a planned cesarean (n = 176) were characterized by more advanced age and a higher prevalence of diabetes in the subsequent pregnancy. Furthermore, they had more often experienced operative vaginal delivery, severe perineal lacerations, and severe neonatal complications at the index delivery.

CONCLUSIONS

The incidence of shoulder dystocia among nulliparous women with vaginal delivery was 1.0% with a 7.2% risk of recurrence in a population where about 50% had a subsequent birth and of these 78% had subsequent vaginal delivery. Important risk factors for recurrence were low maternal height, increase of birthweight ≥250 g from index to subsequent delivery and operative vaginal delivery.

Influence of Sonographic Fetal Weight Estimation Inaccuracies in Macrosomia on Perinatal Outcome

OBJECTIVE

 To evaluate the influence of inaccurate sonographic fetal weight estimation in macrosomia on the mode of delivery and neonatal outcome (NO).

METHODS

 In 14 633 pregnancies between 2002 and 2016, this retrospective study evaluated the association between sonographic fetal weight estimation, true birth weight (BW), mode of delivery (primary cesarean section [pCS], secondary cesarean section, vaginal delivery, and operative vaginal delivery rates) and NO parameters (5-min Apgar < 7, pH < 7.1, neonatal intensive care unit [NICU] admission, shoulder dystocia). Singleton pregnancies > 37 + 0 weeks with ultrasound-estimated fetal weight (EFW) within 7 days before delivery were included. The study population was divided into four groups: Group 1 (false-negative): EFW < 4000 g/BW ≥ 4000 g; Group 2 (true-positive): EFW ≥ 4000 g/BW ≥ 4000 g; Group 3 (false-positive): EFW ≥ 4000 g/BW < 4000 g; and Group 4 (true-negative): EFW < 4000 g/BW < 4000 g.

RESULTS

 As expected, the highest secondary cesarean section (sCS) rate was found in Group 2 (true-positive) (30.62 %), compared with only 17.68 % in Group 4 (true-negative). The sCS rate in the false-positive Group 3 was significantly higher (28.48 %) in comparison with the false-negative Group 1 (21.22 %; OR 1.48; 95 % CI, 1.16 to 1.89; P = 0.002). In comparison with the true-negative Group 4, univariate analyses showed significantly higher rates for sCS in all other groups: odds ratio (OR) 2.06 for Group 2 (95 % CI, 1.74 to 2.42; P < 0.001), 1.85 for Group 3 (95 % CI, 1.54 to 2.22, P < 0.001), and 1.25 for Group 1 (95 % CI, 1.05 to 1.49; P < 0.01). No significant differences were found for NO between Groups 1 and 3 for the parameters 5-min Apgar < 7 (P = 0.75), pH < 7.1 (P = 0.28), or NICU admission (P = 0.54). However, there was a significantly higher chance for shoulder dystocia in Group 1 compared with Group 3 (OR 4.58; 95 % CI, 1.34 to 24.30; P = 0.008).

CONCLUSION

 Sonographic EFW inaccuracies in fetal macrosomia appear to have a greater impact on the mode of delivery than birth weight itself. Underestimation of fetal weight may be associated with a higher probability of shoulder dystocia.

Accelerated fetal growth velocity across the third trimester is associated with increased shoulder dystocia risk among fetuses who are not large-for-gestational-age: A prospective observational cohort study

OBJECTIVE

To investigate whether fetuses with accelerated third trimester growth velocity are at increased risk of shoulder dystocia, even when they are not large-for-gestational-age (LGA; estimated fetal weight (EFW) >95th centile).

METHODS

Fetal growth velocity and birth outcome data were prospectively collected from 347 nulliparous women. Each had blinded ultrasound biometry performed at 28 and 36 weeks' gestation. Change in EFW and abdominal circumference (AC) centiles between 28-36 weeks were calculated, standardised over exactly eight weeks. We examined the odds of shoulder dystocia with increasing EFW and AC growth velocities among women with 36-week EFW ≤95th centile (non-LGA), who went on to have a vaginal birth. We then examined the relative risk (RR) of shoulder dystocia in cases of accelerated EFW and AC growth velocities (>30 centiles gained). Finally, we compared the predictive performances of accelerated fetal growth velocities to 36-week EFW >95th centile for shoulder dystocia among the cohort planned for vaginal birth.

RESULTS

Of the 226 participants who had EFW ≤95th centile at 36-week ultrasound and birthed vaginally, six (2.7%) had shoulder dystocia. For each one centile increase in EFW between 28-36 weeks, the odds of shoulder dystocia increased by 8% (odds ratio (OR [95% Confidence Interval (CI)]) = 1.08 [1.04-1.12], p<0.001). For each one centile increase in AC between 28-36 weeks, the odds of shoulder dystocia increased by 9% (OR[95%CI] = 1.09 [1.05-1.12], p<0.001). When compared to the rest of the cohort with normal growth velocity, accelerated EFW and AC velocities were associated with increased relative risks of shoulder dystocia (RR[95%CI] = 7.3 [1.9-20.6], p = 0.03 and 4.8 [1.7-9.4], p = 0.02 respectively). Accelerated EFW or AC velocities predicted shoulder dystocia with higher sensitivity and positive predictive value than 36-week EFW >95th centile.

CONCLUSIONS

Accelerated fetal growth velocities between 28-36 weeks' gestation are associated with increased risk of shoulder dystocia, and may predict shoulder dystocia risk better than the commonly used threshold of 36-week EFW >95th centile.

Diagnostic accuracy of modified Hadlock formula for fetal macrosomia in women with gestational diabetes and pregnancy weight gain above recommended

OBJECTIVES

Women with gestational diabetes (GDM) and weight gain during pregnancy above recommended more often give birth to macrosomic children. The goal of this study was to evaluate the diagnostic accuracy of the modified formula for ultrasound assessment of fetal weight created in a pilot study using a similar specimen in comparison to the Hadlock-2 formula.

METHODS

This is a prospective, cohort, applicative, observational, quantitative, and analytical study, which included 213 pregnant women with a singleton pregnancy, GDM, and pregnancy weight gain above recommended. Participants were consecutively followed in the time period between July 1st, 2016, and August 31st, 2020. Ultrasound estimations were made within three days before the delivery. Fetal weights estimated using both formulas were compared to the newborns' weights.

RESULTS

A total of 133 fetal weight estimations were made. In comparison to the newborns' weight modified formula had significantly smaller deviation in weight estimation compared to the Hadlock-2 formula, higher frequency of deviation within 5% of newborns weights (78.2% [95% CI=0.74-0.83] vs. 60.2%), smaller frequency of deviations from 5 to 10% (19.5 vs. 33.8%) and above 10%, which was even more significant among macrosomic children. There were 36/50 (72%) correctly diagnosed cases of macrosomia by modified and 33/50 (66%) by Hadlock-2 formula. Area under the curve (AUC) for the modified formula was 0.854 (95% CI=0.776-0.932), and for the Hadlock-2 formula 0.824 (95% CI=0.740-0.908). The positive predictive value of the modified formula was 81.81%, the negative 97.91%.

CONCLUSIONS

In cases of greater fetal weights, the modified formula showed greater precision.

Fetal weight estimation by automated three-dimensional limb volume model in late third trimester compared to two-dimensional model: a cross-sectional prospective observational study

Background

Accurate estimation of fetal weight is important for prenatal care and for detection of fetal growth abnormalities. Prediction of fetal weight entails the indirect measurement of fetal biometry by ultrasound that is then introduced into formulae to calculate the estimated fetal weight. The aim of our study was to evaluate the accuracy of fetal weight estimation of Chinese fetuses in the third trimester using an automated three-dimensional (3D) fractional limb volume model, and to compare this model with the traditional two-dimensional (2D) model.

Methods

Prospective 2D and 3D ultrasonography were performed among women with singleton pregnancies 7 days before delivery to obtain 2D data, including fetal biparietal diameter, abdominal circumference and femur length, as well as 3D data, including the fractional arm volume (AVol) and fractional thigh volume (TVol). The fetal weight was estimated using the 2D model and the 3D fractional limb volume model respectively. Percentage error was defined as (estimated fetal weight - actual birth weight) divided by actual birth weight and multiplied by 100. Systematic errors (accuracy) were evaluated as the mean percentage error (MPE). Random errors (precision) were calculated as ±1 SD of percentage error. The intraclass correlation coefficient (ICC) was used to analyze the inter-observer reliability of the 3D ultrasound measurements of fractional limb volume.

Results

Ultrasound examination was performed on 56 fetuses at 39.6 ± 1.4 weeks’ gestation. The average birth weight of the newborns was 3393 ± 530 g. The average fetal weight estimated by the 2D model was 3478 ± 467 g, and the MPE was 3.2 ± 8.9. The average fetal weights estimated by AVol and TVol of the 3D model were 3268 ± 467 g and 3250 ± 485 g, respectively, and the MPEs were − 3.3 ± 6.6 and − 3.9 ± 6.1, respectively. For the 3D TVol model, the proportion of fetuses with estimated error ≤ 5% was significantly higher than that of the 2D model (55.4% vs. 33.9%, p < 0.05). For fetuses with a birth weight < 3500 g, the accuracy of the AVol and TVol models were better than the 2D model (− 0.8 vs. 7.0 and − 2.8 vs. 7.0, both p < 0.05). Moreover, for these fetuses, the proportions of estimated error ≤ 5% of the AVol and TVol models were 58.1 and 64.5%, respectively, significantly higher than that of the 2D model (19.4%) (both p < 0.05). The inter-observer reliability of measuring fetal AVol and TVol were high, with the ICCs of 0.921 and 0.963, respectively.

Conclusion

In this cohort, the automated 3D fractional limb volume model improves the accuracy of weight estimation in most third-trimester fetuses. Prediction accuracy of the 3D model for neonatal BW, particularly < 3500 g was higher than that of the traditional 2D model.

Care of Infants Born to Women with Diabetes

PURPOSE OF REVIEW

Infants of women with diabetes are at risk for specific morbidities including congenital anomalies, abnormalities of fetal growth, neonatal hypoglycemia, electrolyte abnormalities, polycythemia, hyperbilirubinemia, and respiratory distress syndrome. Recent studies have shed light on long-term outcomes of these infants and presented advances in treatment. The purpose of this review is to outline the most common neonatal morbidities affecting infants of women with diabetes, the pathophysiology and prevalence of these conditions, and contemporary approaches to treatment.

RECENT FINDINGS

Recent investigative findings have led to advances in treatment approaches for these infants, particularly regarding risks of neonatal hypoglycemia. Optimizing maternal glycemic control during pregnancy is imperative to improving infant outcomes. However, on a population level, maternal diabetes still poses significant risks to the infant. Timely and appropriate treatment of infants of women with diabetes is imperative to decrease short- and long-term morbidity.

Pregestational diabetes in pregnancy: Complications, management, surveillance, and mechanisms of disease-A review

Diabetes is an increasingly common diagnosis among pregnant women. Pregestational diabetes is associated with an increase in many adverse pregnancy outcomes, which impact both on the woman and her fetus. The models of pregnancy care for women with diabetes are based largely on observational data or consensus opinion. Strategies for aneuploidy screening and monitoring for fetal well-being should be modified in women with diabetes. There is an increasing understanding of the mechanisms by which congenital anomalies and disorders of fetal growth occur, involving epigenetic modifications, changes in gene expression in critical developmental pathways, and oxidative stress. This knowledge may lead to pathways for improved care for these high-risk pregnancies.

Ultrasound Fetal Weight Estimation in Diabetic Pregnancies

OBJECTIVES

To evaluate different formulas for estimating fetal weight in diabetic pregnancies.

METHODS

This retrospective study evaluated the precision of ultrasound fetal weight estimation in 756 pregnancies complicated by gestational diabetes between 2002 and 2016. The estimated fetal weights (EFWs) were obtained within 7 days of delivery from 10 weight estimation formulas and were compared with pair-wise matched controls from 15,701 patients. The precision of the evaluated formulas for EFW was analyzed by median absolute percentage errors (MAPEs), mean percentage errors (MPEs), and proportions of estimates within 10% of actual birth weight.

RESULTS

Among the tested formulas, the lowest MAPE was detected with formula I of Hadlock et al (Am J Obstet Gynecol 1985; 151:333-337), and the formula of Schild et al (Ultrasound Obstet Gynecol 2004; 23:30-35) had the highest proportion of estimates within the 10% range. The EFW in diabetic patients showed a slight trend toward overestimation in comparison with the matched controls (MPE estimates showed a trend toward more positive values). In most of the EFW formulas that were evaluated, no significant differences were detected in MAPEs and estimates within the 10% range. The MPE estimates with most formulas in both groups were close to zero. Overall, the differences between most of the evaluated formulas were small.

CONCLUSIONS

Little evidence was found for differences in the accuracy of the EFW in diabetic pregnancies and controls. The Hadlock I formula showed the lowest MAPE, and the Schild formula had the highest proportion of estimates within the 10% range.

Optimal Timing of Prenatal Ultrasound in Predicting Birth Weight in Diabetic Pregnancies

OBJECTIVE

This study sought to determine the optimal timing of ultrasound in the third trimester to predict birth weight accurately in diabetic women with a singleton pregnancy.

METHODS

A retrospective cohort study of all diabetic women with a singleton pregnancy treated in Halifax, Nova Scotia, was performed. Estimated fetal weight was derived from ultrasound measures using the Hadlock2 equation. The Mongelli equation was used to predict birth weight. The association between gestational age at ultrasound and accuracy of predicted birth weight was assessed, with accuracy as a continuous variable representing the difference between predicted and actual birth weight and as a categorical variable (with four gestational age categories) representing whether predicted birth weight was within, over, or under 250 g of actual birth weight RESULTS: The cohort of 943 women comprised 121 (12.8%) with type 1 diabetes, 111 (11.7%) with type 2 diabetes, and 711 (75.4%) with gestational diabetes. Ultrasound scans performed at term were the most accurate in predicting birth weight. At this gestational age, the mean difference between predicted and actual birth weight was -30 g (95% confidence interval -109 to -48). After adjusting for maternal body mass index, age, smoking, type of diabetes, and interval between ultrasound examination and delivery, accuracy improved as gestational age at ultrasound increased (P = 0.005). The odds of underpredicting or overpredicting birth weight were not significantly affected by the timing of the ultrasound examination.

CONCLUSION

Because the predictive accuracy of ultrasound prediction of birth weight improves with gestational age, fetal growth assessment at term is recommended to aid with delivery planning in women with diabetes.

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.

Fractional fetal thigh volume in the prediction of normal and abnormal fetal growth during the third trimester of pregnancy

Background

Currently, 2-dimensional ultrasound estimation of fetal size rather than fetal growth is used to define fetal growth restriction, but single estimates in late pregnancy lack sensitivity and may identify small for gestational age rather than growth restriction. Single or longitudinal measures of 3-dimensional fractional thigh volume may address this problem.

Objective

We sought to derive normal values for 3-dimensional fractional thigh volume in the third trimester, determine if fractional thigh volume is superior to 2-dimensional ultrasound biometry alone for detecting fetal growth restriction, and determine whether individualized growth assessment parameters have the potential to identify fetal growth restriction remote from term delivery.

Study Design

This was a longitudinal prospective cohort study of 115 unselected pregnancies in a tertiary referral unit (St Mary’s Hospital, Manchester, United Kingdom). Standard 2-dimensional ultrasound biometry measurements were obtained, along with fractional thigh volume measurements (based on 50% of the femoral diaphysis length). Measurements were used to calculate estimated fetal weight (Hadlock). Individualized growth assessment parameters and percentage deviations in longitudinally measured biometrics were determined using a Web-based system (iGAP; http://iGAP.research.bcm.edu). Small for gestational age was defined <10th and fetal growth restriction <3rd customized birthweight centile. Logistic regression was used to compare estimated fetal weight (Hadlock), estimated fetal weight (biparietal diameter–abdominal circumference–fractional thigh volume), fractional thigh volume, and abdominal circumference for the prediction of small for gestational age or fetal growth restriction at birth. Screening performance was assessed using area under the receiver operating characteristic curve.

Results

There was a better correlation between fractional thigh volume and estimated fetal weight ((biparietal diameter–abdominal circumference–fractional thigh volume) obtained at 34-36 weeks with birthweight than between 2-dimensional biometry measures such as abdominal circumference and estimated fetal weight (Hadlock). There was also a modest improvement in the detection of both small for gestational age and fetal growth restriction using fractional thigh volume–derived measures compared to standard 2-dimensional measurements (area under receiver operating characteristic curve, 0.86; 95% confidence interval, 0.79–0.94, and area under receiver operating characteristic curve, 0.92; 95% confidence interval, 0.85–0.99, respectively).

Conclusion

Fractional thigh volume measurements offer some improvement over 2-dimensional biometry for the detection of late-onset fetal growth restriction at 34-36 weeks.

Frequency of fetal macrosomia and the associated risk factors in pregnancies without gestational diabetes mellitus

INTRODUCTION

There has been an increased incidence of macrosomic newborns in the world and most of the macrosomic newborns are born from non-GDM pregnant women. The objective of this study was to determine the frequency and the associated risk factors of fetal macrosomia in non-GDM pregnant women.

METHODS

A total 4246 consequtive pregnant women who had no GDM was included the study population. Data was collected from hospital database of Balikesir State Hospital between January 2014 and January 2015. Statistical analysis was carried out using the independent samples t-test and chi-squared test. Logistic regression analysis was used to determine the relationships between associated risk factors and the presence of fetal macrosomia. In this analysis, fetal macrosomia was taken as the dependent variable and associated risk factors were taken as independent variables. Results are shown as odds ratios (ORs) (95% CI) in the logistic regression analysis.

RESULTS

366 of the 4246 pregnant women were diagnosed with fetal macrosomia (8.6%). Compared the control women, a statistically significant correlation between fetal macrosomia and pre-pregnancy body mass index (BMI), gestational weight gain (GWG), parity, advanced maternal age, and male fetal sex was found. Maternal BMI, and GWG were the two risk factors most strongly associated with macrosomia.

CONCLUSION

The prevalance of fetal macrosomia is rising among Turkish women. High pre-pregnancy BMI and GWG represent main modifiable risk factors for macrosomia and need more attention from health care providers.

Correlation of ultrasonographic estimated fetal weight with actual birth weight in a tertiary hospital in Lagos, Nigeria

BACKGROUND

Sonographic fetal weight estimation is an important component of antenatal care.

AIM

To sonographically estimate fetal weight at term and to compare estimated with actual birth weights to determine the validity of estimated fetal weights.

SUBJECTS AND METHODS

In the prospective study, a convenience sample of 282 women was recruited. Ethical approval and informed consent of patients were obtained. An experienced sonographer estimated fetal weights by measuring BPD, HC, AC and FL using a scanner with Hadlock 3 weight estimation model. Actual birth weights were measured with a Crown weighing scale by a midwife. Data was analyzed with SPSS software version 17.0 while descriptive and inferential statistics were used to interpret results. Results were tested at error level set at p≤ 0.05.

RESULTS

Mean estimated and actual birth weights were 3378±40g and 3393±60g respectively. Difference between the two means was not significant. Eleven percent of fetuses were sonographically estimated to be microsomic while 14.5% were microsomic at birth; 12.1% were sonographically estimated to be macrosomic but 15.2% were macrosomic at birth. Most macrosomic fetuses were delivered through cesarean section(CS) and fetal weights increased with maternal age and parity.

CONCLUSION

Sonographically estimated fetal weight using Hadlock 3 weight estimation model without validation correlated positively with actual birth weight in a Nigerian population.

A modified prenatal growth assessment score for the evaluation of fetal growth in the third trimester using single and composite biometric parameters

OBJECTIVE

To define modified Prenatal Growth Assessment Scores (mPGAS) for single and composite biometric parameters and determine their reference ranges in normal fetuses.

METHODS

Nine anatomical parameters (ap) were measured and the weight estimated (EWTa, EWTb) in a longitudinal study of 119 fetuses with normal neonatal growth outcomes. Expected third trimester size trajectories, obtained from second trimester Rossavik size models, were used in calculating Percent Deviations (% Dev's) and their age-specific reference ranges in each fetus. The components of individual % Dev's values outside their reference ranges, designated +iapPGAS, -iapPGAS, were averaged to give +apPGAS and -apPGAS values for the 3rd trimester. The +iapPGAS and -iapPGAS values for different combinations of ap (c1a (HC, AC, FDL, ThC, EWTa), c1b (HC, AC, FDL, ThC, EWTb), c2 (ThC, ArmC, AVol, TVol), c3 (HC, AC, FDL, EWTa)) were then averaged to give +icPGAS and -icPGAS values at different time points or at the end of the third trimester (+cPGAS, -cPGAS). Values for iapPGAS, ic1bPGAS, and ic2PGAS were compared to their respective apPGAS or cPGAS reference ranges.

RESULTS

All mPGAS values had one 95% range boundary at 0.0%. Upper boundaries of 1D +apPGAS values ranged from 0.0% (HC) to +0.49% (ThC) and were +0.06%, +2.3% and +1.8% for EWT, AVol and TVol, respectively. Comparable values for -apPGAS were 0.0% (BPD, FDL, HDL), to -0.58% (ArmC), -0.13% (EWT), -0.8% (AVol), and 0.0% (TVol). The +cPGAS, 95% reference range upper boundaries varied from +0.36% (c1b) to +0.89% (c2). Comparable values for -cPGAS lower boundaries were -0.17% (c1b) to -0.43% (c2).

CONCLUSIONS

The original PGAS concept has now been extended to individual biometric parameters and their combinations. With the standards provided, mPGAS values can now be tested to see if detection of different types of third trimester growth problems is improved.

Birth weight and neonatal adiposity prediction using fractional limb volume obtained with 3D ultrasound

INTRODUCTION

The objective of this investigation was to study fetal thigh volume throughout gestation and explore its correlation with birth weight and neonatal body composition. This novel technique may improve birth weight prediction and lead to improved detection rates for fetal growth restriction.

MATERIALS AND METHODS

Fractional thigh volume (TVol) using 3D ultrasound, fetal biometry and soft tissue thickness were studied longitudinally in 42 mother-infant pairs. The percentages of neonatal body fat, fat mass and fat-free mass were determined using air displacement plethysmography. Correlation and linear regression analyses were performed.

RESULTS

Linear regression analysis showed an association between TVol and birth weight. TVol at 33 weeks was also associated with neonatal fat-free mass. There was no correlation between TVol and neonatal fat mass. Abdominal circumference, estimated fetal weight (EFW) and EFW centile showed consistent correlations with birth weight. Thigh volume demonstrated an additional independent contribution to birth weight prediction when added to the EFW centile from the 38-week scan (p = 0.03).

CONCLUSION

Fractional TVol performed at 33 weeks gestation is correlated with birth weight and neonatal lean body mass. This screening test may highlight those at risk of fetal growth restriction or macrosomia.

Fetal macrosomia: risk factors, maternal, and perinatal outcome

BACKGROUND

Macrosomia is defined as birth-weight over 4,000 g irrespective of gestational age and affects 3-15% of all pregnancies. Aim The present study aimed to determine the relationship between mother's characteristics and macrosomic births and also compare macrosomic and normal newborns regarding the maternal and offspring complications of diabetes during pregnancy.

SUBJECTS AND METHODS

In this case control study, among the 420 consecutive births occurring in public and private hospitals of Shiraz, Iran from October 2006 to March 2007, the data of 32 macrosomic and 128 normal newborns were analyzed using t-test and chi square in bivariate and logistic regression in multivariate model.

RESULTS

The mean (SD) of neonate weight, height, and head size was 3323.4 (709), 48.95 (3.2), and 34.9 (1.8), respectively. Regression analysis showed that gestational diabetes (Odds Ratio (OR): 11.9, Confidence Interval (CI): 4.6-30.3), preeclampsia in the pregnancy period due to diabetes (OR: 3.81, CI: 1.1-13.2), and macrosomic birth history (OR: 3.3, CI: 1.04-10.4) were the main predictors of macrosomia. Moreover, macrosomia increased neonate hypoglycemia (OR: 4.7, CI: 1.4-15.8) and section delivery (OR: 4.1, CI: 1.27-13.1).

CONCLUSION

Gestational diabetes, preeclampsia due to diabetes, and history of macrosomic birth were the main predictors of macrosomia. Moreover, macrosomia increased some delivery complications for both mothers and newborns.

Prediction of fetal macrosomia: effect of sonographic fetal weight-estimation model and threshold used

OBJECTIVE

To compare the accuracy of 21 sonographic fetal weight-estimation models and abdominal circumference (AC) as a single measure for the prediction of fetal macrosomia (> 4000 g) using either fixed or optimal model-specific thresholds.

METHODS

A total of 4765 sonographic weight estimations performed within 3 days prior to delivery were analyzed. The predictive accuracy of 21 published sonographic fetal weight-estimation models was calculated using three different thresholds: a fixed threshold of 4000 g; a model-specific threshold obtained from the inflexion point of the receiver-operating characteristics (ROC) curve; and a model-specific threshold associated with the highest overall accuracy. Cluster analysis was used to determine whether a certain combination of fetal biometric indices is associated with a higher predictive accuracy than others.

RESULTS

For a fixed threshold of > 4000 g, there was considerable variation among the models in sensitivity (range, 13.6-98.5%) and specificity (range, 63.6-99.8%) for fetal macrosomia. Use of the threshold derived from the inflexion point of the ROC curve decreased the intermodel variation to a minimum (sensitivity, 84.4-91.4%; and specificity, 79.5-86.3%). Even when this optimal model-specific threshold was applied, models based on three to four biometric indices were more accurate than were models based on only two biometric indices or on AC as a single measure (P=0.03).

CONCLUSIONS

Sonographic fetal weight-estimation models based on three to four biometric indices appear to be more accurate than are models based on two indices or on AC as a single measure, for the diagnosis of macrosomia. In these cases, the use of an optimal, model-specific threshold is associated with a higher degree of accuracy than is the uniform use of a fixed threshold of an estimated weight of > 4000 g.

[Obstetrical care in gestational diabetes and management of preterm labor]

OBJECTIVES

Search for data necessary to elaborate recommendations for obstetrical care in gestational diabetes and management of preterm labor.

METHODS

Systematic review of the literature and levels of evidence.

RESULTS

In case of gestational diabetes and in the absence of disease or other risk factor associated, there is no evidence to support a systematic rate of clinical follow up different from other pregnancy. The relevance of ultrasound estimates of fetal weight is limited. No formula is superior to others or to the simple measurement of abdominal circumference for the prediction of macrosomia (EL3). The usefulness of the research septal hypertrophy is not demonstrated (EL4). The systematic application of umbilical Doppler has no proven benefits in the absence of growth restriction or hypertension associated (EL4). Monthly ultrasound monitoring of the fetus can be proposed for diabetics on insulin or poorly controlled. In cases of gestational diabetes controlled by diet, cardiotocography of fetal heart rate has not proven useful. In poorly controlled diabetes and/or on insulin, the registration may be discussed taking into account other risk factors associated (EL4). A weekly recording of fetal heart rate is often recommended in case of type 2 diabetes discovered during pregnancy. In case of preterm labor, calcium channel blockers and oxytocin antagonists can be used without specific precautions. The risk of using beta-adrenergic outweighs the benefit. Administration of corticosteroid can be done under glycemic control, with insulin therapy if necessary. Screening test for gestational diabetes should not be performed within few days after last steroid injection.

Defining normal and abnormal fetal growth: promises and challenges

Normal fetal growth is a critical component of a healthy pregnancy and influences the long-term health of the offspring. However, defining normal and abnormal fetal growth has been a long-standing challenge in clinical practice and research. We review various references and standards that are used widely to evaluate fetal growth and discuss common pitfalls of current definitions of abnormal fetal growth. Pros and cons of different approaches to customize fetal growth standards are described. We further discuss recent advances toward an integrated definition for fetal growth restriction. Such a definition may incorporate fetal size with the status of placental health that is measured by maternal and fetal Doppler velocimetry and biomarkers, biophysical findings, and genetics. Although the concept of an integrated definition appears promising, further development and testing are required. An improved definition of abnormal fetal growth should benefit both research and clinical practice.

A new algorithm for improving fetal weight estimation from ultrasound data at term

Objective

The purpose of this retrospective study was to find a method of improving the accuracy of fetal birth weight estimation on the basis of traditional ultrasonographic measurements of the head, thorax, and femur at term. In this context, we analyzed a novel regression method comparing to existing algorithms.

Methods

The delivery records of two hospitals were searched for women who delivered macrosomic infants, and the patients’ medical records were retrospectively reviewed in order to derive clinical and ultrasonographic data at term. A total of 223 patients with macrosomic infants (birth weight > 4,000 g) were identified. These patients were complemented by data for 212 women who had ultrasound fetal assessments of less than 4,000 g. We used the method of isotonic regression to construct a birth weight prediction function that increases monotonically with each of the input variables and which minimizes the empirical quadratic loss.

Results

A suspicion of macrosomia was based on a history of macrosomia, fundal height, and sonographic weight estimation >4,000 g. The mean period between ultrasound weight estimation and delivery was 7.2 days. The ability of the biometric algorithms developed to predict fetal weight at term ranged between a mean absolute error of 312 and 344 g, given a confidence interval of 95%. We demonstrate that predictions of birth weight on the basis of ultrasound data can be improved significantly, if an isotonic regression model is used instead of a linear regression model.

Conclusions

This study demonstrates that ultrasound detection of macrosomia can be improved using the isotonic regression method.

Macrosomia: a new formula for optimized fetal weight estimation

OBJECTIVES

To develop and test a specific formula for estimating weight in the macrosomic fetus.

METHODS

Ultrasound estimations of fetal weight were carried out within 1 week of delivery in 424 singleton fetuses with a birth weight of > or = 4000 g. Exclusion criteria were multiple pregnancy, intrauterine death and major structural or chromosomal anomalies. Stepwise regression modeling was used to derive a prediction formula with birth weight as the dependent variable and maternal booking weight and fetal biometric measurements as independent parameters. After a new formula for estimated fetal weight (EFW) had been developed in a formula-finding group (n = 284), it was compared with commonly used weight equations (evaluation group, n = 140).

RESULTS

The new formula (log(e)EFW = 7.6377445039 + 0.0002951035 x maternal weight + 0.0003949464 x head circumference + 0.0005241529 x abdominal circumference + 0.0048698624 x femur length) proved to be superior to established equations, with the smallest mean error (mean +/- SD, -10 +/- 202 g), the smallest mean percentage error (mean +/- SD, -0.03 +/- 4.6%) and the lowest mean absolute percentage error (3.69 (range, 0.05-13.57)%) when studied in the evaluation group. With the new formula, 77.9% of estimates fell within +/- 5% of the actual weight at birth, 97.1% within +/- 10%, and 100% within +/- 15% and +/- 20%.

CONCLUSIONS

The new formula allows better weight estimation in the macrosomic fetus.

Fetal size and growth velocity in the prediction of the large for gestational age (LGA) infant in a glucose impaired population

OBJECTIVES

To evaluate the performances of estimated fetal weight (EFW) and fetal growth velocity (FGV) in the prediction of birth weight>95th centile amongst women with impaired glucose tolerance (IGT); the prediction of neonatal hypoglycaemia was a secondary endpoint.

STUDY DESIGN

Two hundred and forty-two consecutive women (61 type 1 diabetes mellitus, 14 type 2 diabetes mellitus, 49 gestational diabetics and 118 with impaired glucose tolerance) receiving routine care at the combined diabetes/antenatal clinic, Jessop Hospital for Women, Sheffield. EFW was routinely calculated at approximately two-week intervals in the third trimester with the last EFW prior to delivery used in the analysis. FGV was calculated from two estimates of fetal weight between 21 and 35 days apart. EFW and FGV were both expressed as standard deviation (Z) scores.

RESULTS

The mean gestational age at delivery was 37 weeks (range 26-40 weeks). Sixty-five (27%) infants were of birth weight>95th centile. Mean EFW Z scores were 2.7 and 0.99 for >95th and <95th centile, respectively (p<0.001). Receiver operator characteristics (ROC) curve analysis gave area under the curve 0.8; using a cut-off Z score of 1.7 (=95.5 centile), EFW has sensitivity 80% and specificity 72% in predicting an LGA neonate (likelihood ratios 2.8 and 0.27 for positive and negative test). Mean FGV Z scores were 0.85 and 0.4 for >95th and <95th centile, respectively (p>0.05); ROC curve analysis indicated no discriminatory capacity. Estimates of fetal size and growth performed poorly in the prediction of neonatal hypoglycaemia.

CONCLUSION

In routine clinical practice, EFW has limited utility in the prediction of the LGA infant. FGV does not identify the LGA infant. EFW and FGV do not predict neonatal hypoglycaemia.

Prediction of risk for shoulder dystocia with neonatal injury

OBJECTIVE

The purpose of this study was to develop a predictive model of risk for shoulder dystocia (ShD) with injury.

STUDY DESIGN

Medical records in 3 urban university teaching hospitals were reviewed to identify and characterize 498 cases of ShD, including 90 with neonatal injury and a comparison group with of 622 with vaginal delivery (VgD) without ShD. The data were subjected to logistic regression modeling to find the best combination of variables to discriminate between the injury and VgD groups.

RESULTS

The best model included birth weight in combination with maternal height and weight as well as gestational age and parity. A score over 0.5 detected 50.7% of the shoulder dystocia cases with brachial plexus injury along with a false positive rate of 2.7%.

CONCLUSION

Using a statistical model it is possible to identify adverse combinations of factors that are associated with ShD and neonatal injury along with a relatively low false positive rate.

Risk factors for macrosomia and its clinical consequences: a study of 350,311 pregnancies

OBJECTIVES

To identify demographic risk factors for either birthweight >4kg or over the 90th centile and to quantify the obstetric risks.

STUDY DESIGN

Data from 350,311 completed singleton pregnancies in the North West Thames Region between 1988 and 1997 were analysed using logistic regression. Predisposing factors and pregnancy outcome were compared by birthweight 2.5-4kg (n=259,902) and >4kg (n=36,462) and 10th-90th centile (n=279,780) and >90th centile (n=34,937).

RESULTS

Macrosomia defined as birthweight >90th centile was more likely in women whose BMI >30 (kg/m(2)) (odds ratio (OR) 2.08; confidence intervals (CI) 1.99, 2.17), parity >4 (OR 2.20; CI 2.02, 2.40), age >40 (OR 1.22; CI 1.11, 1.35) and in women with pre-existing diabetes (OR 6.97; CI 5.36, 8.16) or who developed gestational diabetes (OR 2.77; CI 2.51, 3.07). Macrosomia defined by birthweight >4kg was better than birthweight >90th centile at predicting morbidity and was associated with a prolonged first and second stage of labour (OR 1.57; CI 1.51, 1.63) and (OR 2.03; CI 1.88, 2.19), respectively, an increased risk of instrumental vaginal delivery (OR 1.76; CI 1.68, 1.85), third degree perineal trauma (OR 2.73; CI 2.30, 3.23), emergency caesarean section (OR 1.84; CI 1.75, 1.93), postpartum haemorrhage (OR 2.01; CI 1.93, 2.10), Apgar score <4 (OR 1.35; CI 1.03, 1.76), and admission to the special care baby unit (OR 1.51; CI 21.38, 1.68).

CONCLUSION

Macrosomia is more common in mothers who are obese, older or diabetic and is associated with significant obstetric morbidity.

Neonatal anthropometric measurements to predict birth weight by ultrasound

OBJECTIVE

To develop a more accurate ultrasound birth weight (BW) model using neonatal anthropometric measurements.

STUDY DESIGN

Two hundred thirty-one newborns were evaluated. Measurements included weight; head, chest, and abdominal circumferences (umbilicus and liver), humerus, and femur lengths. Infants were randomly assigned into two groups (G(1) and G(2)). Anthropometric measurements that are obtainable by ultrasound were generated from G(1). Stepwise regression and a bootstrap analysis were used to create the prediction models. The models were validated using G(2).

RESULTS

The final stepwise regression model included FL and circumferences of the head, chest, and abdomen. The correlations were: G(1): R(2)=0.91, p<0.001; G(2): R(2)=0.90 p<0.001. There was no difference between derived and actual BW in G(1) (p=0.42) or G(2) (p=0.28). The mean absolute percent error between the prediction model and actual BW was 3.8%.

CONCLUSION

Neonatal anthropometric models are strongly predictive of actual BW. This model will be tested prospectively using ultrasound to predict fetal weight.

Suspected big baby: a difficult clinical problem in obstetrics

BACKGROUND

Large for gestational age fetuses, also called macrosomic fetuses, represent a continuing challenge in obstetrics.

METHODS

We review various problems with large for gestational age fetuses. We have performed a literature search, mainly through the database PubMed (includes the Medline database). The clinical problem is discussed from the primary care provider's, the patient's and the obstetrician's point of view.

RESULTS

Macrosomia is arbitrarily defined as having a fetal weight of above the 90th percentile, a birth weight of above 4000 g or 4500 g, or a birth weight of over +2 standard deviation of the mean birth weight by gestational age. The diagnosis of macrosomia is difficult, both by palpation and symphysis fundus measurement; even with sophisticated sonographic measures. The combination of biparietal diameter, femur length and abdominal circumference appears to be no better than abdominal circumference alone.

INTERPRETATION

Based on the literature, labor should not be induced in nondiabetic pregnancies. The best policy is to await spontaneous birth or to induce labor after 42 weeks completion. A great number of cesarean sections have to be performed to avoid a single case of plexus brachialis paresis resulting from a difficult shoulder delivery. Cesarean section should not be considered in nondiabetic pregnancies unless the estimated fetal weight is above 5000 g. In pregnancies complicated by diabetes mellitus there are reasons for selective induction of labor if macrosomia is suspected and for cesarean section if the calculated birth weight is above 4000 g. Each department should have a strategy to handle such a situation because the problem with the difficult shoulder delivery cannot be completely avoided. Different procedures of managing difficult shoulder delivery are described.

Sonographic estimation of fetal weight in macrosomic fetuses: diabetic versus non-diabetic pregnancies

The objective of this study is to compare the accuracy of sonographic estimation of fetal weight of macrosomic babies in diabetic vs non-diabetic pregnancies. All babies weighing 4,000 g or more at birth, and who had ultrasound scans performed within one week of delivery were included in this retrospective study Pregnancies with diabetes mellitus were compared to those without diabetes mellitus. The mean simple error (actual birthweight--estimated fetal weight); mean standardised absolute error (absolute value of simple error (g)/actual birthweight (kg)); and the percentage of estimated birthweight falling within 15% of the actual birthweight between the two groups were compared. There were 9,516 deliveries during the study period. Of this total 1,211 (12.7%) babies weighed 4,000 g or more. A total of 56 non-diabetic pregnancies and 19 diabetic pregnancies were compared. The average sonographic estimation of fetal weight in diabetic pregnancies was 8% less than the actual birthweight, compared to 0.2% in the non-diabetic group (p < 0.01). The estimated fetal weight was within 15% of the birthweight in 74% of the diabetic pregnancies, compared to 93% of the non-diabetic pregnancies (p < 0.05). In the diabetic group, 26.3 % of the birthweights were underestimated by more than 15 %, compared to 5.4% in the non-diabetic group (p < 0.05). In conclusion, the prediction accuracy of fetal weight estimation using standard formulae in macrosomic fetuses is significantly worse in diabetic pregnancies compared to non-diabetic pregnancies. When sonographic fetal weight estimation is used to influence the mode of delivery for diabetic women, a more conservative cut-off needs to be considered.