Limitations of clinical and sonographic estimates of birth weight: experience with 1034 parturients

Accuracy of Dare's formula in estimating fetal birth weight in pregnant women

OBJECTIVE

To evaluate the accuracy of Dare's formula in estimating fetal birth weight in pregnant women.

METHODS

A prospective study was conducted at a tertiary care hospital in New Delhi after institutional ethical committee clearance. In all, 175 pregnant women with singleton pregnancies of 37 weeks or more were included. The aim was to assess fetal birth weight by Dare's formula and ultrasonography. This estimated fetal weight (EFW) was compared with actual birth weight (ABW) of newborn.

RESULTS

Estimated fetal birth weight by Dare's formula was within 10% of ABW in 77 (44.00%) cases. Meanwhile in the majority (98; 56.00%), EFW by Dare's formula was not within 10% of ABW. The proportion of EFW by ultrasonography within 10% and not within 10% of ABW were comparable (50.29% [88] and 49.71% [87], respectively).

CONCLUSION

Dare's formula can be used by medical personnel as a clinical method in routine prenatal care to estimate fetal weight, for better management of women in labor to decrease the maternal and neonatal mortality and morbidity.

Bias in the prenatal lung measurements in fetal congenital diaphragmatic hernia with intrauterine growth restriction

OBJECTIVES

The failure of a fetus to develop to its full potential due to maternal or placental factors is known as intrauterine growth restriction (IUGR). Fetal head growth is usually preserved in that situation producing a potential discordance between head and body size. Our goal is to discover if IUGR has an impact on the prenatal ultrasound measurements taken to assess pulmonary development in congenital diaphragmatic hernia (CDH).

METHODS

A retrospective chart review (IRB#2017-6361) was performed on all prenatally diagnosed CDH patients from 2007 to 2016. Patient demographics, fetal and neonatal anthropometric measurements, and fetal lung parameters were the main subjects of the data that were gathered. Fetal growth was assessed by the curves based on US data by Olsen et al. and by Peleg et al. Of 147 CDH patients, 19 (12.9 %) patients were diagnosed with IUGR before the 30th gestational week while there were 20 (13.6 %) patients after the 30th gestational week.

RESULTS

Patients with IUGR and the observed-to-expected lung-to-head ratio (O/E LHR) less than 25 % had better survival rates both to discharge and date compared to non IUGR group (p=0.226, OR 2.25 95 % CI 0.60-1.08 and p=0.175, OR 2.40 95 % CI 0.66-1.17, respectively). Moreover, the ECMO need of the patients who had IUGR and O/E LHR less than 25 % was significantly less than the patients without IUGR (38.5 vs. 80.0 %, p=0.005).

CONCLUSIONS

This study confirms that the intrauterine measurements to predict pulmonary hypoplasia in CDH patients are misleading in the presence of IUGR and cause an overestimation.

Are Junior Residents Accurate at Predicting Fetal Weight? An Analysis of Junior Residents' Performance of Estimated Fetal Weight Using Ultrasound and Leopold's Maneuver

Background

Performing accurate estimated fetal weights (EFWs) is a critical skill developed in obstetrics residency training. Resident physicians are often the first to perform EFWs on obstetric patients when they enter care. Evaluating residents' accuracy in performing EFWs is crucial for assessing their achievement in residency training milestones and providing patient care.

Methods

As part of an educational initiative program between 2014 and 2020, postgraduate year 1 (PGY1) and postgraduate year 2 (PGY2) residents performed EFW measurements on 10 term (>37w0d) patients using ultrasound and Leopold's maneuver and 10 preterm (>24w0d and <37w0d) patients using ultrasound. Clinical characteristics, mode of delivery, and actual birthweights (BWs) were recorded for each patient. The accuracy of these estimates was evaluated using mixed-effect regression models.

Results

Thirty-three residents, 1127 deliveries, and 1790 EFW measurements were evaluated. Overall, the percentage of residents with estimations within 10% of actual BW went up in PGY2 for Leopold's and ultrasound term births, but not for preterm ultrasound births. Maternal body mass index and actual BW were associated with absolute percentage estimation error. After adjusting for these variables, there was a statistically significant decrease in error between PGY1 and PGY2 for Leopold's method in term births; ultrasound (term and preterm) showed more modest reductions in error during PGY2.

Discussion

Resident physicians have accurate estimates of EFWs early in their training, beginning in their first year of residency by both Leopold's maneuver and ultrasound. Furthermore, PGY2 residents performed better than PGY1 residents for Leopold's method.

The Rate of Intrapartum Cesarean Delivery Based on Estimated Fetal Weight in Comparison to Previous Child's Birth Weight

OBJECTIVE

 The aim of the study is to examine whether an estimated fetal weight of the current pregnancy greater than previous birth weight is associated with increased odds of intrapartum cesarean delivery.

STUDY DESIGN

 We conducted a retrospective cohort study of all women who had more than one singleton pregnancy at 23 weeks' gestation or greater at a single labor and delivery unit. We only analyzed the second pregnancy in the dataset. We excluded women who had preterm birth in the second pregnancy. Women were categorized according to the difference between estimated fetal weight and previous birth weight-estimated fetal weight close to previous birth weight within 500 g (similar weight group); estimated fetal weight significantly (more than 500 g) greater than previous birth weight (larger weight group); and estimated fetal weight significantly (more than 500 g) lower than previous birth weight (smaller weight group). The primary outcome was intrapartum cesarean delivery. Multivariable logistic regression was performed to calculate adjusted odds ratios (aORs) with 95% confidence interval (95% confidence interval [CI]) after adjusting for predefined covariates.

RESULTS

 Of 1,887 women, there were 1,415 (75%) in the similar weight group, 384 (20%) in the greater weight group, and 88 (5%) in the smaller weight group. Individuals in the larger weight group compared with those in the similar weight group had higher odds of undergoing intrapartum cesarean delivery (11.2 vs. 4.5%; aOR 2.91; 95% CI 1.91-4.45). The odds of intrapartum cesarean delivery in the smaller weight group compared with those in the similar weight group were not increased (3.4 vs. 4.5%; crude OR 0.75; 95%CI 0.23-2.42).

CONCLUSION

 The difference between current estimated fetal weight and previous birth weight plays an important role in assessing the risk of intrapartum cesarean delivery.

KEY POINTS

· Estimated fetal weight compared with previous birth weight is an important factor.. · Cesarean delivery is infrequent if estimated fetal weight is similar to previous birth weight.. · Larger estimated fetal weight greater than the previous birth weight is associated with cesarean delivery..

Admission ultrasonography as a means of identifying unrecognized fetal compromise in term singleton pregnancies at the onset of labor - a feasibility study

OBJECTIVES

Apparently uncomplicated low-risk pregnancies, especially first time births, account for a significant proportion of adverse birth outcomes. Improved risk stratification with a simple bedside scan on admission in early labor could potentially reduce adverse intrapartum outcomes. The aim of this feasibility study was to assess a cohort of low-risk subjects with admission ultrasonography at the onset of labor with a view to conducting a future randomized controlled trial (RCT). The objectives were three-fold; i) to determine the logistics of performing a labor admission ultrasound scan ii) to establish whether abnormal ultrasound features can be identified and iii) whether they are associated with emergency delivery and/or poor condition of the neonate at birth.

METHODS

We performed a prospective cohort study of 295 participants with term singleton cephalic pregnancies admitted in early labor or for labor induction with non-fetal indications. The setting was a university teaching hospital in Ireland with almost 8000 births annually. A bedside ultrasound scan was performed to assess fetal biometry, amniotic fluid volume and placental maturity. Patients and their babies were followed up until hospital discharge. The outcomes of interest included image quality, time to perform a scan, oligohydramnios (Single Deepest Pool ≤ 2 cm), small for gestational age (SGA; abdominal circumference <10th centile), mature placenta (Grannum 2 or 3), pathological CTG, emergency cesarean section (CS), fetal acidosis (cord arterial pH <7.10 or base excess <-12.0), low Apgar score <7 at 5 min and neonatal unit admission.

RESULTS

Image quality was optimal in 274 of the 295 scans (93%) and 271 (92%) were completed in less than 10 min. Of this low-risk population, 67 of 294 (23%) had oligohydramnios, 11 (4%) were small for gestational age and 87 (30%) had a mature placenta (Grannum grade 2). The incidence of pathological CTG and emergency CS was higher among patients with oligohydramnios than those with a normal scan but did not reach statistical significance; Odds Ratio 3.40 (95% Confidence Intervals 0.55 to 20.92) and OR 1.43 (95% CI 0.66 to 3.08) respectively. The mean birthweight was significantly lower in those with oligohydramnios -139 g (95% CI -248 to -30) and admission scan detected SGA -357 g (95% CI -557 to -137). Adverse perinatal outcomes were uncommon with a higher incidence of fetal acidosis (pH < 7.10) in the oligohydramnios group. The incidence of neonatal unit admission >24 h was higher in the oligohydramnios group but not statistically significant; OR 3.75 (95% CI 0.61 to 22.97). Results for SGA alone were non-significant and results for oligohydramnios and SGA combined were similar to those for oligohydramnios alone.

CONCLUSIONS

Admission ultrasonography is feasible in a routine clinical setting, but evidence of benefit is weak and does not currently justify a randomized controlled trial.

A Rational and Standardized Prenatal Examination

Importance

As prenatal care is in transition after the COVID-19 pandemic, reviewing fundamental physical examination approaches is necessary for providers examining obstetrical patients.

Objective

The objective of this review is 3-fold: (1) convey why the age of telemedicine necessitates reconsideration of the standardized physical examination in routine prenatal care; (2) identify the screening efficacy of examination maneuvers used within a standard prenatal examination of the neck, heart, lungs, abdomen, breasts, skin, lower extremities, pelvis, and fetal growth; and (3) propose an evidence-based prenatal physical examination.

Evidence Acquisition

A comprehensive literature review identified relevant research, review articles, textbook chapters, databases, and societal guidelines.

Results

We conclude that an evidence-based prenatal examination for asymptomatic patients includes the following maneuvers: inspection and palpation for thyromegaly and cervical lymphadenopathy, cardiac auscultation, fundal height measurement, and a pelvic examination for purposes including testing for gonorrhea and chlamydia, assessing pelvimetry, and assessing cervical dilation later in the pregnancy, intrapartum, or in the setting of ultrasonogram-detected prelabor preterm cervical shortening.

Conclusions and Relevance

Although not true of all physical examination maneuvers, this article demonstrates that there are maneuvers that continue to play important screening roles in asymptomatic patients. With the increase in virtual visits and fewer in-person prenatal appointments, the rational basis for maneuvers recommended in this review should inform decision making around the prenatal examination performed.

Accuracy of ultrasound estimation of fetal weight at term: A comparison of shepard and hadlock methods

Background

Ultrasound measurement provides a noninvasive means of obtaining information about fetal weight and may help in necessary preparations at and after delivery. Although some ultrasound methods include only one or two fetal indices, others, to improve accuracy, incorporate either three or all the four fetal indices. The aim of this report is to assess the accuracy of two different methods for fetal weight estimation.

Materials and Methods

This was a prospective study of 170 consecutive pregnant women at term. Ultrasound was used to estimate fetal weight by the Shepard and Hadlock methods, and the actual birth weight (ABW) was determined at birth. The ultrasound-estimated fetal weights (EFWs) and ABW were analyzed.

Results

The women were aged 21-42 years (mean 31.3 ± 7 years). The EFW using the Shepard method was 1.9 kg-5.0 kg (mean 3.6 ± 0.5 kg) and 1.8 kg-4.4 kg (mean 3.3 ± 0.4 kg) for Hadlock method, and ABW was 2.0 kg-4.5 kg (mean 3.4 ± 0.5 kg). The mean EFW using the Shepard method was significantly higher than that of ABW (P < 0.001). The Shepard method significantly overestimated macrosomia compared to that by the ABW. There was no significant difference in microsomia rate between the two methods and ABW.

Conclusion

The Hadlock method was more accurate at estimating fetal weight compared to the Shepard method and is recommended for the ultrasound estimation of fetal weight in our setting and similar settings.

Accuracy of ultrasound in estimating fetal weight in New Zealand

Introduction

Ultrasound estimation of fetal weight is an important factor guiding antenatal management. We aimed to review the accuracy of ultrasound in predicting fetal weight and birthweight category and identify influencing factors.

Methods

We performed a retrospective study of term pregnant women who underwent ultrasound within 7 days of delivery at National Women's Health between January 2019 and January 2020. Stillbirths, major fetal anomalies and multiple pregnancies were excluded. Estimated fetal weight (EFW) was calculated using Hadlock formula and compared with birthweights. We evaluated change in weight categories due to these errors.

Results

Of 560 fetuses included, three quarters (n = 425, 76%) of EFWs were within 10% of birthweight. 135 fetuses had EFWs either less than 90% (n = 19) or greater than 110% (n = 116). Fetuses with EFW < 90% had longer times between scanning and delivery, lower EFW and higher maternal BMI. Fetuses with EFW > 110% were associated with higher EFW, later gestational age and older maternal age. US incorrectly estimated 71 (12.7%) fetal birthweight categories. Underestimated weight category (8.9%) was associated with higher maternal BMI.

Discussion

Inaccurate EFWs were more common at the extremes of fetal weight. A significant association was underestimation birthweight in mothers with increased BMI, who are at increased risk for perinatal and surgical complications.

Conclusion

Our accuracy of 76% correctly predicted EFWs compares favourably with previous studies. Clinicians and sonographers should be aware of the increased risk for inaccurate categorisation of fetuses at the extremes of EFW and in mothers with increased BMI.

Fetal weight estimation in tall women: is ultrasound more accurate than clinical assessment? A prospective trial

PURPOSE

Estimated fetal weight (EFW) is crucial for clinical decision-making during pregnancy and labor. Maternal habitus impacts its accuracy. This study compared the accuracy of clinical versus ultrasound EFW in tall pregnant women (height ≥ 172 cm, 90th percentile).

METHODS

In this prospective study, tall pregnant women at term, who arrived for a prenatal visit and delivered within a week, underwent clinical and ultrasound assessments of estimated fetal weight. Each woman served as her own control. After delivery, birth weight was compared to the clinical and ultrasound EFW. The primary outcome was the accuracy of each method in predicting the actual birth weight.

RESULTS

All 100 women included in this trial underwent clinical and ultrasound estimations of fetal weight. Mean maternal height was 175.7 ± 3.3 (172-185) cm. More clinical EFW swere inaccurate compared to ultrasound (25 (25%) vs. 6 (6%), respectively, p < 0.001). Both clinical (3583 g) and ultrasound (3490 g) evaluations underestimated the fetal weights compared to the birth weights (3664 g, p < 0.001). In the macrosomic fetal group, both the clinical (3983 g) and ultrasound (3767 g) estimates were significantly inaccurate compared to the birth weights (4237 g, p < 0.001).

CONCLUSION

Among tall women, ultrasound EFW is more accurate than clinical EFW.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

IRB-0016-17-MMC, Clinical-Trials.gov identifier NCT03206281.

Trends of changes in the specific contribution of selected risk factors for shoulder dystocia over a period of more than two decades

Objectives Shoulder dystocia (SD) is an obstetrical emergency with well-recognized risk factors. We aimed to identify trends of changes in the specific contribution of risk factors for SD over time. Methods A nested case control study comparing all singleton deliveries with and without SD was undertaken. A multivariable logistic regression model was used in order to identify independent risk factors for SD and a comparison of the prevalence and the specific contribution (odds ratio (OR)) of the chosen risk factors in three consecutive eight-year intervals from 1988 to 2014 was performed. Results During the study period, there were 295,946 deliveries. Of them 514 (0.174%) were complicated with SD. Between 1988 and 2014 the incidence of SD has decreased from 0.3% in 1988 to 0.1% in 2014. Using a logistic regression model grandmultiparity, diabetes mellitus (DM), fetal weight, and large for gestational age (LGA) were found to be independent risk factors for SD (OR 1.25 95% CI 1.04-1.51, p=0.02; OR 1.53 95% CI 1.19-1.97, p=0.001; OR 1.002 95% CI 1.001-1.002, p < 0.001; OR 3.88 95% CI 3.09-4.87, p < 0.001; respectively). While the OR for grandmultiparity, fetal weight, and LGA has significantly changed during the study period with a mixed trend, the OR of DM has demonstrated a significant linear increase over time. Conclusions The individual contribution of selected risk factors for the occurrence of SD has significantly changed throughout the years. The contribution of DM has demonstrated a linear increase over time, emphasizing the great impact of DM on SD.

THIRD TRIMESTER ULTRASOUND SCAN COMBINED WITH A CLINICAL METHOD FOR ACCURATE BIRTHWEIGHT PREDICTION AT TERM: A COHORT STUDY IN SPAIN

OBJECTIVE

To develop and assess an equation based on maternal clinical parameters and third trimester ultrasound biometry (combined method), and compare it with ultrasound-estimated foetal weight (EFW) calculated using the Hadlock 2 formula.

METHODS

Cohort study. A total of 1,224 women with singleton pregnancies who had undergone foetal ultrasound scanning (USS) at 34 weeks were recruited. The study was conducted at a reference center in Valencia (Spain) between January and December 2016. A gestation-adjusted projection (GAP) method was applied to estimated foetal-weight-for-gestational-age by foetal gender at delivery (EFWa). A multivariate regression was created to estimate foetal weight at term (EFWmr) using anthropometric, demographic, ultrasonographic and obstetric-neonatal variables. EFWa and EFWmr were calculated and compared with actual birthweight.

RESULTS

The proportion for EFWmr within <10% of actual birthweight was greater than EFWa (82% vs. 65%, p<0.001). The mean relative error in foetal-weight predictions by using EFWmr was reduced from 6.7% to 0.9% (difference 5.7% 95% CI: 5.4 to 6.0) paired t-test p<0.001, significantly improving the accuracy attainable with USS. The EFWmr outperformed the GAP method in predicting birthweight, within 1% relative error. For new- borns <2,500 g, the proportion of estimates within <10% of the actual birthweight for the EFWmr was greater than that of the EFWa (20.4 vs. 16.3%, p=0.005). For babies with normal birthweight (2,500-3,999 g), EFWmr was a better predictor of birthweight than EFWa (84.5 vs. 65.7%, p<0.001).

CONCLUSIONS

Mathematical modelling to predict birthweight improves third trimester routine ultrasound measurement to estimate neonatal weight at term.

Antenatal detection of fetal growth restriction and risk of stillbirth: population-based case-control study

OBJECTIVES

Antenatal surveillance of intrauterine growth aims to detect growth-restricted fetuses (FGR), which face increased risk of stillbirth. Improving their detection could be an effective strategy for prevention of stillbirth. The French REPERE study was conducted to estimate the association between antenatal detection of FGR and risk of stillbirth.

METHODS

REPERE is a case-control study performed in three French districts with a combined total of approximately 30 000 births annually. Cases were singleton small-for-gestational-age (SGA) stillbirths ≥ 24 weeks' gestation and without severe congenital anomaly, between 2012 and 2014, identified using a population-based stillbirth registry; controls were live births fulfilling the same inclusion criteria over a 9-week period from 7 April to 8 June 2014. Data were extracted by trained investigators from medical records and ultrasound reports. SGA was defined as birth weight < 10^th percentile of French customized standards. FGR was defined by the presence of at least one of seven predefined parameters (suspected FGR mentioned in medical records or in ultrasound report, suspected faltering growth mentioned in an ultrasound report, documented abdominal circumference or estimated fetal weight < 10^th percentile, referral for additional ultrasound examination to monitor growth or abnormal umbilical artery Doppler). We used logistic regression to estimate crude and adjusted odds ratios (ORs) for the association between detection of FGR and risk of stillbirth. Included covariables were parity, maternal medical history, vascular complications during pregnancy and birth-weight percentile, which are known to be associated with risk of detection of FGR and of stillbirth.

RESULTS

During the study period, there were 92 182 births ≥ 22 weeks' gestation, including 669 stillbirths, of which 79 were singleton SGA stillbirths ≥ 24 weeks and without severe congenital anomaly. Of these cases, 44.3% (35/79) had FGR detected, compared with a detection rate of 36.2% in controls (154/426). The crude OR expressing the association between detection of FGR and risk of stillbirth was 1.4 (95% CI, 0.9-2.3) and the OR adjusted for parity, presence of risk factors for FGR, presence of vascular disorder and birth-weight percentile was 0.6 (95% CI, 0.3-1.0). Among deliveries ≥ 28 weeks, detection rates were 38.3% vs 36.0% for cases and controls, with an adjusted OR of 0.5 (95% CI, 0.2-1.0).

CONCLUSION

Antenatal detection of FGR was protective against stillbirth, but over 40% of stillbirths among SGA fetuses occurred despite detection of FGR, pointing to the need to improve management following detection. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Effects of gestational diabetes mellitus on risk of adverse maternal outcomes: a prospective cohort study in Northwest Ethiopia

Background

Gestational diabetes mellitus is a leading medical condition woman encounter during pregnancy with serious short- and long-term consequences for maternal morbidity. However, limited evidence was available on potential impacts of gestational diabetes mellitus using updated international diagnostic criteria on adverse maternal outcomes. Therefore, this study aimed to assess the effects of gestational diabetes mellitus on the risk of adverse maternal outcomes in Northwest Ethiopia.

Methods

A prospective cohort study was conducted among pregnant women followed from pregnancy to delivery. Gestational diabetes mellitus status was determined by using a two-hour 75 g oral glucose tolerance test and based on updated international diagnostic criteria. Multivariable log-binomial model was used to examine the effects of gestational diabetes mellitus on the risk of adverse maternal outcomes.

Results

A total of 694 women completed the follow-up and included in the analysis. Women with gestational diabetes mellitus had a higher risk of composite adverse maternal outcome (ARR=1.58, 95% CI: 1.22, 2.04), caesarean delivery (ARR=1.67; 95%: 1.15, 2.44), pregnancy induced hypertension (ARR= 3.32; 95%: 1.55, 7.11), premature rupture of membranes (ARR= 1.83; 95%: 1.02, 3.27), antepartum hemorrhage (ARR= 2.10; 95%: 1.11, 3.98) and postpartum hemorrhage (ARR= 4.85; 95%:2.28, 10.30) compared to women without gestational diabetes mellitus.

Conclusions

Gestational diabetes mellitus increased the risk of adverse maternal outcomes. This implies that maternal care and intervention strategies relating to women with gestational diabetes mellitus should be strengthened.

Intrapartum prediction of birth weight with a simplified algorithmic approach derived from maternal characteristics

Objective To derive and validate a population-specific multivariate approach for birth weight (BW) prediction based on quantitative intrapartum assessment of maternal characteristics by means of an algorithmic method in low-risk women. Methods The derivation part (n = 200) prospectively explored 10 variables to create the best-fit algorithms (70% correct estimates within ±10% of actual BW) for prediction of BW at term; vertex presentation with engagement. The algorithm was then cross validated with samples of unrelated cases (n = 280) to compare the accuracy with the routine abdominal palpation method. Results The best-fit algorithms were parity-specific. The derived simplified algorithms were (1) BW (g) = 100 [(0.42 × symphysis-fundal height (SFH; cm)) + gestational age at delivery (GA; weeks) - 25] in nulliparous, and (2) BW (g) = 100 [(0.42 × SFH (cm)) + GA - 23] in multiparous. Cross validation showed an overall 69.3% accuracy within ±10% of actual BW, which exceeded routine abdominal palpation (60.4%) (P = 0.019). The algorithmic BW prediction was significantly more accurate than routine abdominal palpation in women with the following characteristics: BW 2500-4000 g, multiparous, pre-pregnancy weight <50 kg, current weight <60 kg, height <155 cm, body mass index (BMI) <18.5 kg/m2, cervical dilatation 3-5 cm, station <0, intact membranes, SFH 30-39 cm, maternal abdominal circumference (mAC) <90 cm, mid-upper arm circumference (MUAC) <25 cm and female gender of the neonates (P < 0.05). Conclusion An overall accuracy of term BW prediction by our simplified algorithms exceeded that of routine abdominal palpation.

Two-dimensional fetal biometry versus three-dimensional fractional thigh volume for ultrasonographic prediction of birthweight

OBJECTIVE

To develop and validate birthweight prediction models using fetal fractional thigh volume (TVol) in an Indian population, comparing them with existing prediction models developed for other ethnicities.

METHODS

A prospective observational study was conducted among 131 pregnant women (>36 weeks) attending a tertiary hospital in New Delhi, India, for prenatal care between December 1, 2014, and November 1, 2016. Participants were randomly divided into formulating (n=100) and validation (n=31) groups. Multiple regression analysis was performed to generate four models to predict birthweight using various combinations of two-dimensional (2D) ultrasonographic parameters and a three-dimensional (3D) ultrasonographic parameter (TVol). The best fit model was compared with previously published 2D and 3D models.

RESULTS

The best fit model comprised biparietal diameter, head circumference, abdominal circumference, and TVol. This model had the lowest mean percentage error (0.624 ± 8.075) and the highest coefficient of determination (R² =0.660). It correctly predicted 70.2% and 91.6% of birthweights within 5% and 10% of actual weight, respectively. Compared with previous models, attributability for the 2D and 3D models was 0.65 and 0.55, respectively. Accuracy was -0.05 ± 1.007 and -2.54 ± 1.11, respectively.

CONCLUSION

Models that included TVol provided good prediction of birthweight in the target population.

Neonatal Morbidity of Small- and Large-for-Gestational-Age Neonates Born at Term in Uncomplicated Pregnancies

OBJECTIVE

To compare morbidity among small-for-gestational-age (SGA; birth weight less than the 10th percentile for gestational age), appropriate-for-gestational-age (AGA; birth weight 10th to 90th percentile; reference group), and large-for-gestational-age (LGA; birth weight greater than the 90th percentile) neonates in apparently uncomplicated pregnancies at term (37 weeks of gestation or greater).

METHODS

This secondary analysis, derived from an observational obstetric cohort of 115,502 deliveries, included women with apparently uncomplicated pregnancies of nonanomalous singletons who had confirmatory ultrasound dating no later than the second trimester and who delivered between 37 0/7 and 42 6/7 weeks of gestation. We used two different composite neonatal morbidity outcomes: hypoxic composite neonatal morbidity for SGA and traumatic composite neonatal morbidity for LGA neonates. Log Poisson relative risks (RRs) with 95% CIs adjusted for potential confounding factors (nulliparity, body mass index, insurance status, and neonatal sex) were calculated.

RESULTS

Among the 63,436 women who met our inclusion criteria, SGA occurred in 7.9% (n=4,983) and LGA in 8.3% (n=5,253). Hypoxic composite neonatal morbidity was significantly higher in SGA (1.1%) compared with AGA (0.7%; adjusted RR 1.44, 95% CI 1.07-1.93) but similar between LGA (0.6%) and AGA (adjusted RR 0.84, 95% CI 0.58-1.22). Traumatic composite neonatal morbidity was significantly higher in LGA (1.9%) than AGA (1.0%; adjusted RR 1.88, 95% CI 1.51-2.34) but similar in SGA (1.3%) compared with AGA (adjusted RR 1.28, 95% CI 0.98-1.67).

CONCLUSION

Among women with uncomplicated pregnancies, hypoxic composite neonatal morbidity is more common with SGA neonates and traumatic-composite neonatal morbidity is more common with LGA neonates.

Practice Bulletin No. 173: Fetal Macrosomia

Suspected fetal macrosomia is encountered commonly in obstetric practice. As birth weight increases, the likelihood of labor abnormalities, shoulder dystocia, birth trauma, and permanent injury to the neonate increases. The purpose of this document is to quantify those risks, address the accuracy and limitations of methods for estimating fetal weight, and suggest clinical management for a pregnancy with suspected fetal macrosomia.

The systematic error in the estimation of fetal weight and the underestimation of fetal growth restriction

Fetal growth restriction (FGR) is associated with an increased risk of perinatal morbidity and mortality and has lifetime implications for the risk of chronic medical conditions. Antenatal diagnosis of FGR remains poor, with the majority of cases remaining undiagnosed. Although several factors contribute to the underdiagnosis of FGR, the error in ultrasound estimation of fetal weight (EFW) generally is not considered in clinical practice. In this commentary, we suggest that the intrinsic, or systematic, error in ultrasound EFW is a significant factor contributing to the underestimation of fetuses predicted to have FGR and should be incorporated into screening and surveillance recommendations. To illustrate this point, we present an analytic model of published data from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies characterizing and quantifying the impact of the systematic error in ultrasound EFW on the underdiagnosis of FGR. Independent of the centile at which the risk of adverse outcome related to FGR begins, whether the 10th, 5th or 3rd percentile, our analysis suggests the need to modify to the current paradigm for identifying and responding to fetuses estimated to be at risk.

Ultrasound versus Clinical Examination to Estimate Fetal Weight at Term

Introduction At term, fetal weight estimation is an important factor for decisions about the delivery mode and the timing of labor induction. This study aimed to compare the accuracy of abdominal palpation with that of ultrasound performed by different examiners to estimate fetal weight. The study investigated whether differences in the examiners' training affected fetal weight estimates. The accuracy of the weight estimates made for fetuses with extreme birth weights was also evaluated. Finally, the accuracy of Johnson's method and of Insler and Bernstein's formula for estimating fetal weight were compared with the other two methods. Methods This prospective study included singleton pregnancies between 37 weeks of gestation and 12 days post-term planned for vaginal delivery or cesarean section. Ultrasound and abdominal palpation using Leopold's maneuvers were performed by examiners with different levels of professional experience. Fetal weight was additionally estimated using Insler and Bernstein's formula and Johnson's method. Statistical analysis calculated the accuracy of fetal weight estimates for the different examiners and the four methods. Results A total of 204 women were included in the analysis. Trained ultrasound examiners were most accurate when estimating fetal weight compared with all other examiners. The comparison of all four methods showed that fetal weight was assessed most accurately with ultrasound. No learning curve could be established. BMI and advanced gestational age affected the accuracy of the estimated weight. The analysis showed that a greater deviation between estimated weight and actual weight occurred with all four methods for fetuses at either end of the extremes of fetal weight, i.e., with very low or very high birth weights. Conclusion Fetal weight should be estimated using ultrasound. A good ultrasound training is essential.

Small-for-gestational-age infants among uncomplicated pregnancies at term: a secondary analysis of 9 Maternal-Fetal Medicine Units Network studies

BACKGROUND

Most small (birthweight <10%) for-gestational-age cases occur at term, in uncomplicated pregnancies, and are not identified during prenatal visits as having fetal growth restriction. Hence, they do not benefit from antepartum surveillance and timed delivery. There is dismissive and disquieting opinion that small for gestational age among uncomplicated pregnancies is not associated with increased morbidities and, therefore, does not warrant improved detection. Our hypothesis was that among uncomplicated pregnancies at term, small for gestational age have significantly higher morbidity and mortality than appropriate (birthweight 10-89%) for gestational age.

OBJECTIVE

We sought to compare composite neonatal morbidity among uncomplicated term singleton pregnancies with small vs appropriate for gestational age.

STUDY DESIGN

We culled collected data from 9 completed Maternal-Fetal Medicine Units studies conducted from 1989 through 2004. All data were collected prospectively by trained staff. We excluded women who delivered <37 weeks and those with hypertension or diabetes, multiple gestation, known anomalies, and birthweight of ≥90% for gestational age. Using multivariable analysis, we compared composite neonatal morbidity, which included stillbirth and neonatal mortality between small and appropriate for gestational age. Random effect logistic regressions were used to account for study heterogeneity, with adjustment for potential confounders. We calculated adjusted odds ratios and 95% confidence intervals.

RESULTS

Of the >91,000 women enrolled in the studies, 60% (n = 50,011) met the inclusion criteria. Among the uncomplicated pregnancies, 10.8% (n = 5416) were small for gestational age. The rate of composite neonatal morbidity of 16% in small for gestational age and 10% in appropriate for gestational age persisted (adjusted odds ratio, 1.75; 95% confidence interval, 1.71-1.78). After adjustment for confounders, the following neonatal morbidities were significantly more common among term small than appropriate for gestational age: Apgar <4 at 5 minutes, respiratory distress syndrome, mechanical ventilation, necrotizing enterocolitis grade 2 or 3, and neonatal sepsis. Lastly, rate of stillbirths (3.5 vs 0.9/1000 births; adjusted odds ratio, 3.49; 95% confidence interval, 1.83-6.67) and neonatal mortality (1.1 vs 0.4/1000 births; adjusted odds ratio, 2.56; 95% confidence interval, 1.83-3.57) were significantly more common with small than appropriate for gestational age. In secondary analyses the composite neonatal morbidity among newborns at <5% and at 5-9% was significantly higher than appropriate for gestational age. Lastly, in subgroup analyses of women who delivered at 37.0-38.6 weeks or at ≥39.0 weeks, the increased rate of composite neonatal morbidity, stillbirth, and neonatal mortality among small for gestational age persisted.

CONCLUSION

Among uncomplicated pregnancies at term, small- compared to appropriate-for-gestational-age newborns have a significantly higher likelihood of composite neonatal morbidity, stillbirth, and neonatal mortality. A large multicenter trial is warranted to determine if improved detection of small for gestational age among uncomplicated pregnancies can mitigate morbidities and mortality, without disproportionate interventions and iatrogenic complications.

Predictors of shoulder dystocia at the time of operative vaginal delivery

BACKGROUND

It remains uncertain whether clinical factors known prior to delivery can predict which women are more likely to experience shoulder dystocia in the setting of operative vaginal delivery.

OBJECTIVE

We sought to identify whether shoulder dystocia can be accurately predicted among women undergoing an operative vaginal delivery.

STUDY DESIGN

This was a case-control study of women undergoing a low or outlet operative vaginal delivery from 2005 through 2014 in a single tertiary care center. Cases were defined as women who experienced a shoulder dystocia at the time of operative vaginal delivery. Controls consisted of women without a shoulder dystocia at the time of operative vaginal delivery. Variables previously identified to be associated with shoulder dystocia that could be known prior to delivery were abstracted from the medical records. Bivariable analyses and multivariable logistic regression were used to identify factors independently associated with shoulder dystocia. A receiver operating characteristic curve was created to evaluate the predictive value of the model for shoulder dystocia.

RESULTS

Of the 4080 women who met inclusion criteria, shoulder dystocia occurred in 162 (4.0%) women. In bivariable analysis, maternal age, parity, body mass index, diabetes, chorioamnionitis, arrest disorder as an indication for an operative vaginal delivery, vacuum use, and estimated fetal weight >4 kg were significantly associated with shoulder dystocia. In multivariable analysis, parity, diabetes, chorioamnionitis, arrest disorder as an indication for operative vaginal delivery, vacuum use, and estimated fetal weight >4 kg remained independently associated with shoulder dystocia. The area under the curve for the generated receiver operating characteristic curve was 0.73 (95% confidence interval, 0.69-0.77), demonstrating only a modest ability to predict shoulder dystocia before performing an operative vaginal delivery.

CONCLUSION

While risk factors for shoulder dystocia at the time of operative vaginal delivery can be identified, reliable prediction of shoulder dystocia in this setting cannot be attained.

Three-Versus Two-Dimensional Sonographic Biometry for Predicting Birth Weight and Macrosomia in Diabetic Pregnancies

OBJECTIVES

The purpose of this study was to test the hypothesis that a formula incorporating 3-dimensional (3D) fractional thigh volume would be superior to the conventional 2-dimensional (2D) formula of Hadlock et al (Am J Obstet Gynecol 1985; 151:333-337) for predicting birth weight and macrosomia.

METHODS

We conducted a prospective cohort study of pregnancies complicated by pregestational or gestational diabetes and delivered after 38 weeks. Two-dimensional and 3D sonographic examinations were performed for fetal biometry and factional thigh volumes at 34 to 37 weeks. Fetal weight was estimated by Hadlock's 2D formula IV, which uses only 2D biometry, and formula 6 from Lee et al (Ultrasound Obstet Gynecol 2009; 34:556-565), which incorporates 3D fractional thigh volume and 2D biometry. The gestation-adjusted projection method was used to estimate predicted birth weights from 2D and 3D estimates. The primary outcome was fetal macrosomia, which was defined as birth weight of 4000 g or higher.

RESULTS

A total of 115 women with diabetes met inclusion criteria, and 17 (14.8%) delivered macrosomic neonates. The mean percentage error was significantly lower for the 2D than the 3D projected estimate (1.0% versus 12.0%; P < .01). The standard deviation of the mean percentage error was also significantly lower for the 2D projected estimate (10.2% versus 17.2%; P< .01). Two-dimensional biometry was overall superior to 3D biometry for predicting macrosomia (area under the receiver operating characteristic curve, 0.88 versus 0.75; P = .03). Specificity was significantly higher for 2D biometry (85% versus 66%; P < .01), whereas the difference in sensitivity was not statistically significant (59% versus 71%; P = .22).

CONCLUSIONS

In this study, the Hadlock 2D formula was superior to the 3D method for predicting birth weight and macrosomia in diabetic women when used approximately 2 weeks before delivery, based on the gestation-adjusted projection method.

[Accuracy of ultrasound estimated fetal weight at term]

OBJECTIVES

Our aim was to evaluate the accuracy of estimated fetal weight (EFW) by ultrasound at due date and the factors that could affect it.

METHODS

We performed a retrospective study of 233 patients in 2014. An ultrasound was performed at due date consultation around 41 weeks of amenorrhea by midwives sonographer. EFW was calculated using the Hadlock's formula with 3 parameters (biparietal diameter, abdominal circumference and femur length) and then adjusted including the growth from the due date consultation to the day of delivery (25g/day) and finally compared to birth weight (BW).

RESULTS

The mean absolute weight difference between EFW adjusted and BW was 256g [0; 910]. The mean absolute percentage error was 7.2 % [0; 24.5] and the proportion of the EFW adjusted within 10 % of BW was 69.1 %. There was a strong correlation between EFW adjusted and BW (R=0.79). Obesity in early pregnancy or childbirth, excessive weight gain, the presence of oligoanamnios and fetal macrosomia had no influence on the estimated fetal weight. Indeed, the mean absolute percentage error of child who were macrosome and those were not, was similars (7.9 % vs 7.1 %, P=0.407).

CONCLUSIONS

EFW by ultrasound at due date is performant. However, the adjustment by the effect growth does not improve accuracy. Fetal macrosomia do not decrease the accuracy of ultrasound to estimate the fetal weight at term.

The Use of Ultrasound to Identify Fetuses with Macrosoomia in Diabetic Pregnancies

Diabetic pregnancies are associated with an increased incidence of fetal macrosomia. Prenatal detection of macrosomia is particularly important because of the potential maternal and neonatal morbidity associated with vaginal delivery. Early detection of macrosomia enables the clinician to decease the risk of morbidityeby either fprearing for complications associated with vaginal delivery or changing the timing or route of delivery. M acrosomia is suspected with an estimated faetalweight greate than or eqal to 4,000 g. Two; methods are:used to predict: fetal birth weight The first method is clinical evaluation,:which is based on abdominal palpation of fetal parts and fundatl: size. AThe second metho dis by sonogr aphic examinanon, which is based onfetal biparietal' diameter, abdominal circumferee, and femur length, which are then. plugged into a regression equation to calculat fetal: weight. Clinical techn ques do not relably predict fetal weight. Although ultrasound i's not particularly accurate at determining fetal wiht, it is more reliable than cliniali technique. Ultrasound therefore plays a major role in i;early detectio of m acrsoma. Current research valuates altering or Oexpandingthe use of ultrasound to more accurately-predict macrosomia in infants of diabetic mothers.

Analysis of the effectiveness of ultrasound and clinical examination methods in fetal weight estimation for term pregnancies

Objective:

To compare the accuracy of clinical and ultrasonographic (USG) estimation of fetal weight in non-complicated, term pregnancies.

Materials and Methods:

Two hundred term pregnant women were included in the study. We used three formulae for the estimation of fetal weight at term; the Hadlock formula for the USG method, and two different formulas for clinical methods, maternal symphysis-fundal height and abdominal circumference at the level of umbilicus. Accuracy was determined by mean percentage error, mean absolute percentage error and proportion of estimates within 10% of actual birth weight (birth weight ±10%). Patients were divided into two groups according to actual birth weight, the normal birth weight group (2500-3999 g) and high birth weight group (≥4000 g).

Results:

All three methods statistically overestimated birth weight for the high and normal birth weight groups (p<0.001, p=1.000, p=0.233) (p=0.037, p<0.001, and p<0.001). For both groups, the mean absolute percentage errors of USG were smaller than for the other two clinical methods and the number of estimates were within 10% of actual birth weight for USG was greater than for the clinical methods; the differences were statistically significant (p<0.001). No statistically significant difference of accuracy was observed for all three methods for the high birth weight group (p=0.365, p=0.768, and p=0.540). However, USG systematically underestimated birth weight in this group.

Conclusion:

For estimation of fetal birth weight in term pregnancies, ultrasonography is better than clinical methods. In the suspicion of macrosomia, it must be remembered that no method is better than any other. In addition, if ultrasonography is used, careful management is recommended because ultrasonography overestimates in this group.

Diagnostic accuracy of fundal height and handheld ultrasound-measured abdominal circumference to screen for fetal growth abnormalities

OBJECTIVE

We sought to compare fundal height and handheld ultrasound-measured fetal abdominal circumference (HHAC) for the prediction of fetal growth restriction (FGR) or large for gestational age.

STUDY DESIGN

This was a diagnostic accuracy study in nonanomalous singleton pregnancies between 24 and 40 weeks' gestation. Patients underwent HHAC and fundal height measurement prior to formal growth ultrasound. FGR was defined as estimated fetal weight less than 10%, whereas large for gestational age was defined as estimated fetal weight greater than 90%. Sensitivity and specificity were calculated and compared using methods described elsewhere.

RESULTS

There were 251 patients included in this study. HHAC had superior sensitivity and specificity for the detection of FGR (sensitivity, 100% vs 42.86%) and (specificity, 92.62% vs 85.24%). HHAC had higher specificity but lower sensitivity when screening for LGA (specificity, 85.66% vs 66.39%) and (sensitivity, 57.14% vs 71.43%).

CONCLUSION

HHAC could prove to be a valuable screening tool in the detection of FGR. Further studies are needed in a larger population.

[Accuracy of ultrasound estimated fetal weight performed by residents at delivery day]

Ultrasound fetal weight estimation (EFW) has become a routine practice in obstetrics with a major impact on obstetrical management.

OBJECTIVES

To evaluate the accuracy of sonographic fetal weight estimations performed by residents in obstetrics at the delivery day and to search parameters influencing this exam.

METHODS

A prospective study performed in 299 patients at 37 weeks of gestation or more, during their delivery day. Ultrasound fetal weight estimations were performed by residents and compared to birth weights (BW). The estimated fetal weight (EFW) was calculated using the formula of Hadlock: Log10 EPF=1,335+0.0316 BIP+0,0457 PA+0,1623 LF-0,0034 PA LF.

RESULTS

Mean absolute difference between EFW and BW was 200g [100-450]. Mean absolute percentage error was 5.71 % [2.7-11.37]. The proportion of the EFW within 10 % of BW was 69.6 %. There was a good correlation between EFW and BW (R=0.79). Obesity and fetal macrosomia had negatively influenced ultrasound performance. For the diagnosis of macrosomia, ultrasound has a sensibility of 38 % and a specificity of 99.59 %.

CONCLUSION

Ultrasound fetal weight estimations performed by residents in the delivery room were as accurate as those performed by experimented sonographers. Thus, the predictive performance remains limited with a low sensitivity in the diagnosis of macrosomia.

The utility of ultrasound surveillance of fluid and growth in obese women

OBJECTIVE

The purpose of this study was to evaluate the utility of ultrasound surveillance in obese women.

STUDY DESIGN

This is a retrospective cohort of all obese women who underwent sonography at a single center from 2005-2013. Inclusion criteria were body mass index ≥30 kg/m(2), singleton, ≥1 ultrasound scan performed at <20 weeks of gestation, and ≥1 ultrasound scan performed at ≥24 weeks of gestation. Pregnancies with medical complications, fetal anomalies, or preterm premature rupture of membranes were excluded. Outcomes that were considered were small for gestational age, large for gestational age (LGA), macrosomia, oligohydramnios, and polyhydramnios. We calculated the number needed to screen (NNS) and 95% confidence interval (CI) for scans that were performed during 3 gestational age ranges (24-31 weeks 6 days, 32-35 weeks 6 days, and ≥36 weeks).

RESULTS

Two thousand two sonograms were performed in 1164 obese women at ≥24 weeks of gestation. Small for gestational age was diagnosed in 59 pregnancies (5.1%); 7 pregnancies (0.6%) were diagnosed at <32 weeks of gestation (NNS, 159; 95% CI, 69-490). LGA was diagnosed in 38 cases (3.3%); only 1 case was identified at <32 weeks of gestation and was not LGA at birth. For every 29 (95% CI, 19-46) scans performed at >36 weeks of gestation, 1 case of macrosomia was identified. Amniotic fluid abnormalities were diagnosed in 44 pregnancies (3.8%; oligohydramnios, 19; polyhydramnios, 25); 34.1% abnormalities were diagnosed at <32 weeks of gestation (NNS: oligohydramnios, 113; 95% CI, 55-282 for oligohydramnios; polyhydramnios, 100; 95% CI, 50-230). At ≥36 weeks of gestation, 7 (95% CI, 6-8) scans were needed to diagnose any fluid or growth abnormality.

CONCLUSION

In obese women without comorbidities, few sonographic diagnoses of amniotic fluid or fetal growth abnormalities are made at <32 weeks of gestation. Therefore, if a policy of serial sonographic surveillance is used, we suggest ultrasound scans for fluid and growth in obese women to begin at ≥32 weeks of gestation.

Dietary and lifestyle advice for pregnant women who are overweight or obese: the LIMIT randomized trial

Overweight and obesity during pregnancy are common and are associated with an increased risk of adverse health outcomes for both the mother and the infant. However, robust evidence about the effect of antenatal dietary and lifestyle interventions on health outcomes is lacking. We conducted a multicenter, randomized trial, recruiting 2,212 women (from 3 public maternity hospitals across South Australia) with a singleton pregnancy between 10⁺⁰ and 20⁺⁰ weeks' gestation and a BMI ≥25. The women were randomized to lifestyle advice (n = 1,108) or standard care (n = 1,104). Women randomized to lifestyle advice participated in a comprehensive dietary and lifestyle intervention over the course of their pregnancy (delivered by research staff), while women randomized to standard care received pregnancy care according to local guidelines, which did not include such information. Provision of the lifestyle intervention was associated with a significant 18% relative risk reduction in the chance of infants being born with a birth weight above 4 kg. No other significant differences were identified in maternal pregnancy and birth outcomes between the two treatment groups. Observational studies highlight the association between a high infant birth weight and the subsequent risk of childhood and adulthood obesity. Antenatal interventions that are effective in reducing high infant birth weights therefore represent a significant strategy to tackle obesity from a population health perspective, while ongoing interrogation of the biospecimens and measurements, including ongoing childhood follow-up, will provide a unique opportunity to evaluate the mechanistic pathways of maternal-to-infant/childhood obesity.

Periviable births: epidemiology and obstetrical antecedents

Confusion in terminology and non-standardized definitions can arguably be classified as the most important characteristics that lead to disparate study findings. While such situations abound in all of perinatal epidemiology, the study of "periviable birth" is a classic case in point. The most common term used to describe periviable birth has been extremely low birthweight (ELBW), often defined as newborns with birthweight below 1000g; yet, we identified 11 other descriptors for periviable birth. Due to the multitude of definitions, the reported incidence of periviable births varies from 0.03% to 1.9% (a relative difference of 7025%). Antecedent risk factors for periviable birth, though geographically heterogeneous, include nulliparity and multiple gestations, each accounting for one-third and one-fourth of all periviable births, respectively. Spontaneous preterm labor precedes 34% of these deliveries and premature rupture of membranes in 25%. The pregnancy was complicated by hypertensive disease in 21% and bleeding and chorioamnionitis in 18% each. Over 50% of these births are cesarean deliveries. Six clinical interventions before delivery that may improve outcomes include transfer of patient to a tertiary center, administration of antenatal corticosteroids, tocolytics, or antibiotics after premature rupture of membranes, assessment of fetal well-being with electronic fetal heart rate monitoring, and willingness to perform a cesarean delivery after the limit of viability is reached. While there is an accessible predictive model for mortality and long-term morbidities for newborns delivered at 22-25 weeks with weights of 400-1000g, it is hampered by the need to know the birthweight. In addition to reaching a consensus regarding what birthweight-gestational age thresholds determine a periviable birth, the acute need to optimize neonatal outcomes remains a paramount target worthy of future research, and efforts to advance obstetrical medicine are needed to minimize the likelihood of its occurrence.

Multivariable evaluation of term birth weight: a comparison between ultrasound biometry and symphysis-fundal height

OBJECTIVE

To derive a birth weight predictive equation and to compare its diagnostic value with that of ultrasound.

METHODS

A longitudinal observational cohort study, including singleton pregnancies at term, was performed at St. Orsola-Malpighi Hospital, University of Bologna (Italy). A birth weight prediction formula, including symphysis-fundal height (SFH), BMI, maternal abdominal circumference (mAC) and parity was derived from a general linear model (GLM) (retrospective study). Moreover, on a new series of patients, the fetal weight was estimated by using both GLM and ultrasound using Hadlock formula (prospective study). The residual analysis and the intraclass correlation coefficient (ICC) were used to test the accuracy of methods in predicting birth weight.

RESULTS

Between January and November 2012, 1034 patients were included in the retrospective study and 44 in the prospective one. The following GLM was derived: estimated birth weight (g) = 1485.61 + (SFH (cm) × 23.37) + (11.62 (cm) × mAC) + [BMI × (-6.81)] + (parity (0 = nulliparous, 1 = multiparous) × 72.25). When prospectively applied, the GLM and ultrasound provided a percentage of prediction within ±10% of the actual weight of 73% and 84%, respectively. Ultrasound estimation, as opposite of GLM one, was significantly associated with neonatal weight (R(2 )= 0.388, F = 26.607, p value <0.001, ICC = 0.767).

CONCLUSIONS

Although ultrasound biometry has provided the best values in fetal weight estimation, the predictive performance of both methods is limited.

Early prediction of macrosomia based on an analysis of second trimester amniotic fluid by capillary electrophoresis

AIM

To identify, using capillary electrophoresis and chemometrics, early biomarkers in human amniotic fluid of large-for-gestational-age (LGA) infants.

MATERIALS & METHODS

Second trimester amniotic fluid samples, obtained from mothers undergoing age-related amniocentesis, were analyzed by capillary electrophoresis. Electropherogram data were aligned using correlation-optimized warping. A genetic algorithm using a Bayesian evaluation function and a leave-one-out cross-validation strategy for two birth outcomes: appropriate-for-gestational-age (AGA) versus LGA infants.

RESULTS

LGA (n = 23) was differentiated from AGA (n = 86) with a sensitivity of 100% and a specificity of 98% using only two wavelets. The first wavelet is associated with albumin and the second wavelet with an unknown small molecule.

CONCLUSION

The approach developed herein allows LGA fetuses to be metabolically distinguished from AGA fetuses early in pregnancy and indicates that the birth of a LGA infant is already associated with an altered biochemical profile by the second trimester.

Growth curves: how to best measure growth of the preterm infant

Birth weight is one of the most important anthropometric measures in the evaluation of an infant. For the full-term infant, birth weight is compared with reference or standard growth curves that are constructed by plotting weight, length, and head circumference against postnatal age. Following a similar approach for preterm infants is less effective for a variety of reasons. Birth weight and other anthropometric measures used to evaluate an infant at birth are influenced by various maternal characteristics, the intrauterine milieu, and duration of gestation. Second, the causes of premature birth and their impact on birth weight are largely unknown. Third, gestational age is difficult to determine with full certainty. One approach that has been used to circumvent these issues is to use intrauterine growth reference curves. However, these curves do not really reflect "normal" growth because they were constructed using cross-sectional data from infants born prematurely and, as such, do not reflect the normal condition. Thus, there is a need to develop normative growth curves derived from "healthy" preterm infants that can be applied to neonates born prematurely. These should be updated periodically to reflect secular trends in maternal body weight, height, and overall health.

Association of fetal cranial shape with shoulder dystocia

OBJECTIVE

To evaluate whether fetal cranial shape is related to shoulder dystocia.

METHODS

We compared shoulder dystocia cases (n = 18) with controls (normal vaginal deliveries, n = 18) in a retrospective matched-pairs observational study. Subjects were matched for known maternal and fetal risk factors and then evaluated for fetal biometric differences, which were measured by ultrasound near delivery. We tested multivariable risk models to predict shoulder dystocia by logistic regression.

RESULTS

Cases had a smaller estimated occipitofrontal diameter (OFD) (P = 0.02) and a larger biparietal diameter/estimated OFD ratio (P = 0.003). A multivariable model including estimated fetal weight, estimated OFD, maternal weight and diabetes mellitus had sensitivity and specificity of 86% and 95%, respectively, and positive and negative likelihood ratios of 18.9 and 0.15, respectively. Estimated OFD significantly increased the predictive value of the model.

CONCLUSION

A small estimated OFD is a risk factor for shoulder dystocia in the presence of other significant risk factors. A multivariable model including estimated OFD can predict shoulder dystocia in a clinically useful range.

Accuracy of sonographic fetal weight estimation within 14 days of delivery in a Jordanian population using Hadlock formula 1

OBJECTIVES

To assess the accuracy of sonographic fetal weight estimation within 14 days of delivery in a Jordanian population using Hadlock formula 1 in the third trimester.

MATERIALS AND METHODS

Estimated fetal weights and actual fetal weights data were collected from the medical records of pregnant women who had undergone sonographic fetal weight estimation within 14 days of delivery over the period of March 2008 to June 2010. The analysis included 409 Jordanian women; 6 of them had twins, so the study involved estimation of 415 fetal weights, and these were compared to the actual recorded neonatal weights. Using Hadlock formula 1, we compared the estimations with the infants' actual birth weights. The data were analyzed in 2 groups: within 7 days and 8-14 days.

RESULTS

The mean estimated fetal weight was 3,133 ± 475 g (range 1,343-4,420 g). The mean actual birth weight was 3,179 ± 450 g (range 1,300-4,450 g). The mean absolute percentage of error of ultrasound fetal weight estimation for all infants was 6.5%; however, it was 6.1 and 8.2% if the fetus was delivered within 7 days or 8-14 days of sonography, respectively. Overall, 78.8% of fetal weight estimations were within 10% of actual birth weight; however it was 81.3 and 69.9% if the fetus was delivered within 7 days or from 8-14 days of sonography, respectively.

CONCLUSION

The use of Hadlock formula 1 for sonographic fetal weight estimations in Jordanian women showed acceptable results relative to the actual neonatal weight at birth. However, fetal weight estimation was more reliable when performed within 7 days of delivery.

Reducing the risk of shoulder dystocia and associated brachial plexus injury

Despite persisting controversy over shoulder dystocia prediction, prevention, and injury causation, the authors find considerable evidence in recent research in the field to recommend additional guidelines beyond the current American College of Obstetricians and Gynecologists and Royal College of Obstetricians and Gynecologists guidelines to improve clinical practice in managing patients at risk for experiencing shoulder dystocia. In this article, the authors offer health care providers information, practical direction, and advice on how to limit shoulder dystocia risk and, more importantly, to reduce adverse outcome risk.

Which is the most accurate formula to estimate fetal weight in women with severe preterm preeclampsia?

OBJECTIVE

To identify the most accurate formula to estimate fetal weight (EFW) from ultrasound parameters in severe preterm preeclampsia.

METHODS

In a prospective study, serial ultrasound assessments were performed in 123 women with severe preterm preeclampsia. The EFW, calculated for 111 live born, normal, singleton fetuses within 7 days of delivery using 38 published formulae, was compared to the actual birth weight (ABW). Accuracy was assessed by correlations, mean (absolute and signed) (%) errors, % correct predictions within 5-20% of ABW and limits of agreement.

RESULTS

Accuracy was highly variable. Most formulae systematically overestimated ABW. Five Hadlock formulae utilizing three or four variables and Woo 3 formula had the highest accuracy and did not differ significantly (mean absolute % errors 6.8-7.2%, SDs 5.3-5.8%, > 75% of estimations within 10% of ABW and 95% limits of agreement between -18/20% and +14/15%). They were not negatively affected by clinical variables but had some inconsistency in bias over the ABW range. All other formulae, including those targeted for small, preterm or growth restricted fetuses, were inferior and/or affected by multiple clinical variables.

CONCLUSION

In this GA window, Hadlock formulae using three or four variables or Woo 3 formula can be recommended.