Comparison of clinical estimation of fetal weight at the beginning and end of labor.

OBJECTIVE: To compare the accuracy of clinically estimated fetal weight (EFW) obtained at the beginning and end of labor. METHODS: The clinical EFWs obtained by obstetricians at the beginning (initial EFW) and end (repeat EFW) of labor were compared to determine the accuracy of the estimates in 138 women with term pregnancies. RESULTS: The initial clinical EFW was changed by obstetricians in 65% of patients over the course of their labor. There was a 66% chance that the repeat EFW was more accurate than the initial EFW (P=0.003). This increased to 78% when the difference between the initial and repeat EFW was more than 300 g (P=0.04). Duration and speed of labor, and change in fetal station were not correlated with a lower, higher, or more accurate EFW. CONCLUSION: The improved accuracy of a clinical EFW obtained at the end of labor is important for management decisions, such as whether to attempt operative vaginal delivery.     

Clinical and sonographic estimation of fetal weight performed during labor by residents

OBJECTIVE: This study was undertaken to assess the accuracy of both clinical and sonographic estimations of the fetal weight (EFW) performed during the active phase of labor by residents. METHODS: The study protocol consisted of achieving clinical, followed by sonographic EFW by the admitting resident during the active phase of labor. Patients who had an EFW (clinical or sonographic) within the last 2 weeks were excluded from the study. In addition, the effect of the following variables on the accuracy of the EFW were examined: maternal age, maternal weight and body mass index, parity, the Bishop score before obtaining the EFW, gestational age, birth weight, and the postgraduate year of the examiner. The Pearson correlation, chi2 test, and Student t test were the statistical analyses used. We also calculated the sensitivity, specificity, and positive and negative predictive values for clinical and sonographic EFW for detecting macrosomia (birth weight > or = 4000 g). RESULTS: A total of 192 patients participated in this study. The coefficient of correlation between the clinical and sonographic EFW and the actual birth weight was 0.59 (P < .0001) and 0.65 (P < .0001), respectively. Clinical EFW was correct (within +/-10%) in 72% of the cases and the sonographic EFW was correct (within +/-10%) in 74% of the cases. However, the sensitivity of predicting birth weight of 4 kg or more was only 50% for both clinical and sonographic EFW, with 95% and 97% specificity, respectively. None of the clinical variables that were tested were significantly associated with the accuracy of the EFW. CONCLUSION: Both clinical and sonographic EFW performed during the active phase of labor by residents correlate with the actual birth weight but have poor sensitivity in detecting macrosomic fetuses. Sonographic EFWs offer no advantage over clinical EFWs.     

Accuracy of estimated fetal weight in shoulder dystocia and neonatal birth injury

OBJECTIVE: This study was undertaken to determine whether there is any difference in the rate of error of estimated fetal weight (EFW) in cases of shoulder dystocia compared with controls. STUDY DESIGN: Women whose delivery was complicated by shoulder dystocia were studied and compared with a control group matched for parity, race, labor type (spontaneous or induced), and birth weight (BW). Accuracy (%) was defined as [(EFW-BW)/BW] x 100. The primary outcome of the study was rate of EFW underestimation error 20% or greater. RESULTS: During the 5-year study period, there were 206 cases of shoulder dystocia that met all study criteria. There was no difference in the number of patients that had EFW underestimation error 20% or greater (shoulder dystocia 9.8% vs control 12.8%; P = .38). There was also no difference in the number of patients that had EFW underestimation error 20% or greater between shoulder dystocia with and without injury (injury 8.3% vs no injury 7.1%; P = .79). CONCLUSION: EFW underestimation error in cases of shoulder dystocia is an infrequent event and does not occur more often than in deliveries without shoulder dystocia.     

Ultrasonic estimation of fetal weight at term: an evaluation of eight formulae

AIM: To compare the accuracy of eight sonographic formulae for predicting fetal birth weight at term in a multiethnic population. METHODS: Pregnant women at term who were booked for induction of labor or elective cesarean section were included in the study. Eight ultrasonic fetal biometric formulae were used to predict fetal birth weight. RESULTS: A total of 173 patients were included in the study; 53 (30.6%) patients were from the Indian subcontinent, 44 (25.4%) patients were from Africa, 33 (19.1%) patients were from the Arabian Peninsula and 43 (24.9%) were from other ethnic groups. The mean absolute error ranged from a minimum of 0.3% (+/-11.3) for Hadlock (biparietal diameter [BPD], head circumference [HC], abdominal circumference [AC], femur length [FL]) to a maximum of 37.5% (+/-10.0) for Warsof (FL). The correlation of estimated fetal weight with actual birth weight ranged from a minimum of 0.09 with Warsof (FL) to a maximum of 0.77 with Shepard and Warsof (BPD, AC) and Hadlock (BPD, HC, AC, FL). The combination of AC with BPD measurements rather than FL achieves a high level of accuracy. CONCLUSIONS: Shepard (BPD, AC) provides a simple and accurate logarithm for the prediction of fetal weight at term in the studied multiethnic population.     

Increased composite maternal and neonatal morbidity associated with ultrasonographically suspected fetal macrosomia

Objective: To determine the composite risk of maternal and neonatal morbidity in pregnancies with suspected fetal macrosomia. Methods: In a retrospective study of laboring women delivering singleton, term neonates, we defined 3 groups of patients by estimated fetal weight (EFW) in grams, using ultrasound: (1) <4000, (2) 4000–4499, and (3) 4500+, and tested them for association with a composite outcome using multivariable logistic regression models. The measure of composite morbidity included: shoulder dystocia, third/fourth degree perineal laceration, postpartum hemorrhage, maternal length of stay (LOS)≥ 5 days, neonatal birth trauma, meconium aspiration syndrome, perinatal infection, and neonatal LOS ≥ 5 days. Because of potential interactions between diabetes and birthweight, women with maternal diabetes were examined separately. Results: Of 8,843 deliveries, the proportion with composite morbidity by group was: (1): 26.2%, (2): 41.2%, and (3): 63.6% (p < 0.0001). The OR (95% CI) for groups (2) and (3) were: 1.9 (1.2–2.9) and 2.1 (0.6–7.2), for diabetics (9.7% of the final study population), and 2.3 (1.9–2.7) and 3.9 (2.2–6.9), for non-diabetics. Conclusions: Suspected fetal macrosomia appeared associated with increased risk for a composite measure of childbirth morbidity.     

Placental volume relative to fetal weight estimated by sonography in diabetic pregnancies

Objective: Our purpose was to analyze the fetal weight and placental volume (PV) ratio in diabetic pregnancies during mid-pregnancy.

Method: One hundred and forty nine diabetic pregnancies [75 gestational diabetes mellitus (GDM) and 74 diabetes mellitus type I (T1DM) with good glycemic control] and 232 healthy patients were analyzed by three-dimensional sonographic volumetry of the placenta, while fetal weight was estimated by two-dimensional technique.

Results: The gestational age-specific estimated fetal weight (EFW) [EFWGDM: 1840.8?±?932.82?g; EFWT1DM: 1475.6?±?914.7?g (mean?±?standard deviation) and placental ratio (PR)] was significantly higher (p?<?0.05) in pregnancies complicated by GDM and T1DM (PRGDM: 5.5?±?1.67?g/cm³, PRT1DM: 4.56?±?3.2?g/cm³) compared to control group (Q) (EFWQ: 532?±?186.49?g; PRQ: 2.2?±?0.8?g/cm³), whereas PV was significantly higher (p?<?0.05) only in GDM (PVGDM: 334.3?±?111.5?cm³) compared to control data (PVQ: 232?±?78.9?cm³). In contrast to GDM, T1DM with good glycemic control did not predispose to any changes in placental sonographic volumetric differences compared to control values.

Conclusions: Fetal weight related to the PV is already elevated in second trimester in pregnancies complicated by gestational diabetes mellitus and type I diabetes mellitus compared to normal pregnancies.     

Third trimester abdominal circumference,estimated fetal weight and uterine artery doppler for the identification of newborns small and large for gestational age

Objective

To understand if ultrasound biometric evaluation at 30–32 weeks of gestation is a valuable screening tool for the detection of small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants at birth in a low risk population.

Study design

We enrolled 1848 pregnant women with singleton pregnancy undergoing routine fetal biometry. We divided the infants into four groups: moderate SGA, severe SGA, moderate LGA and severe LGA. We considered third-trimester estimated fetal weight (EFW), abdominal circumference (AC), EFW centile (EFWc), AC centile (ACc) and compared their prediction toward SGA and LGA to determine which of these parameters was the best estimator for fetal size. Then we took the strongest predictive value and added all history-related and ultrasound factors to run a stepdown multivariate logistic regression. All the variables were then dichotomized and sensitivity models only for statistically significant parameters were calculated.

Results

We identified the following predictive factors for each outcome: for severe SGA: EFWc with p < 0.001, uterine artery pulsatility index (UtA PI) with p < 0.002. For moderate SGA: EFWc with p < 0.001, UtA PI with p < 0.004, maternal preeclampsia p < 0.002. For moderate and severe LGA: EFWc with p < 0.001.

Conclusion

We can detect in a low-risk population a group at risk of growth deviations. Adding Doppler velocimetry to 30–32 weeks EFWc improves the specificity (84%) regarding SGA newborns, maintaining a good sensitivity (71%), and reducing the population to be re-screened from 27 to 17%. An ultrasound examination at 34–36 weeks or the clinical assessment of maternal risk factors remain the best tools for LGA newborns.     

The fetal cheek-to-cheek diameter and abdominal circumference: are they correlated?

Objective  The cheek-to-cheek diameter (CCD) has been shown to be an indicator of subcutaneous tissue mass in the fetus. However, the correlation between CCD and the abdominal circumference (AC) has not been investigated yet. The objective of the present study was to demonstrate whether a correlation exists between fetal CCD, AC, estimated fetal weight (EFW), and the 1 h, 50 g, glucose challenge test (GCT) levels in patients with and without gestational diabetes mellitus. Methods  A prospective, institutional review board approved study was performed. The CCD was obtained as part of the ultrasound for obstetric interval growth scans and biophysical profiles. Exams were performed during the third trimester. The CCD was obtained on a coronal view of the fetal face, at the level of the nostrils and lips. Patients were enrolled between November 2005 and May 2006. Pearson correlation coefficient and linear regression modeling were used as appropriate. Results  Eighty-three patients were enrolled, 29 (33%) of them were diabetic. The mean gestational age is 34.8 ± 3 weeks and the mean maternal age is 29.9 ± 5.1. A significant linear association was found between CCD and EFW (Pearson coefficient of correlation being 0.51, P = 0.01). The Pearson correlation coefficient of the relationship between the CCD and AC was 0.47 (P = 0.01). Using a linear regression model, controlling for gestational age at performance of the ultrasound, the association between CCD and EFW remained significant (P = 0.021). There were no significant differences between diabetic and non-diabetic patients regarding the CCD (6.2 ± 0.9 vs. 6.3 ± 0.9 respectively, P = 0.669) or the EFW (2,527.9 ± 705 vs. 2,645 ± 760 g). While AC was significantly correlated with the GCT levels (Pearson coefficient of correlation = 0.46, P = 0.024), no such correlation was demonstrated for CCD (Pearson correlation coefficient = 0.23, P = 0.160). Conclusions  The cheek-to-cheek diameter is significantly correlated to the abdominal circumference and the estimated fetal weight. However, the abdominal circumference has a tighter correlation with the glucose challenge test.     

Defining fetal growth restriction: abdominal circumference as an alternative criterion

Purpose: The purpose of this study is to determine if using abdominal circumference percentile (AC) to define fetal growth restriction (FGR) improves ultrasound at ≥36 weeks as a screening test for small for gestational age (SGA).

Materials and methods: All non-anomalous singletons undergoing ultrasound at a single center at ≥36 weeks during 12/2008–5/2014 were included. FGR was defined as (estimated fetal weight) estimated fetal weight (EFW) and/or abdominal circumference (AC)?Results: There were 1594 ultrasounds. Median (IQR) ultrasound GA was 37.3 (36.6–38.0), days to delivery 10.6 (5.0–18.4), and delivery GA 39.29 (38.6–39.9). EFW <10 had the following characteristics: sensitivity 50.6%, FPR 2.0%, PPV 83.8%, and AUC 0.743. Using AC <10, these were 64.0, 2.9, 81.3, and 0.806, respectively. Using AC or EFW <10, these were 67.5, 3.3, 80.3, and 0.821, respectively; this criterion has the largest AUC (p?Conclusions: AC <10 is more sensitive and has a similar PPV compared with EFW <10 for SGA. Using AC <10 or EFW <10 has the best balance of sensitivity and specificity as a screening test and has a low FPR. AC may be a reasonable alternative criterion to EFW for FGR diagnosis.     

Predictive value of a single early fetal weight estimate in normal pregnancies

OBJECTIVES: To evaluate the accuracy of ultrasound-based fetal weight estimates made at 28-34 weeks of gestation in predicting small- and large-for-gestational-age infants (SGA, LGA) at term. METHODS: Two-hundred and fifty-nine patients with a healthy, singleton pregnancy in whom fetal biometry measurements were routinely performed between 28 and 34 weeks' gestation, were recruited at term delivery. The sonographic estimated fetal weight (EFW) and the birth weight were converted to percentiles on the basis of locally developed growth charts and compared. Multivariate linear stepwise regression analysis was used to predict the birth weight and birth weight percentile. The resulting equation (projectile formula) was used to determine the calculated birth weight, and that value was compared with the actual birth weight. The Bland and Altman plot and Passing and Bablok regression were used to compare between the calculated birth weight and the actual birth weight. RESULTS: Mean gestational age at ultrasound examination was 32+/-1.6 weeks (28-34), and mean age at delivery was 39+/-1.7 weeks (37-42). The multivariate correlation between the calculated birth weight and the birth weight (R2 = 0.524) was higher than the correlation between the sonographic EFW and the birth weight (R2 = 0.083). Both the sonographic EFW and the calculated birth weight are characterized by low positive predictive values in predicting SGA or LGA infants. The calculated birth weight was more accurate in excluding SGA and LGA infants (negative predictive values of 99.5% and 100%, respectively). On method comparison tests, the calculated birth weight was not significantly different than the actual birth weight. CONCLUSIONS: Fetal weight estimation at the early third trimester poorly predicts the birth weight centile at term. It remains uncertain, however, if it would be useful to use the calculated birth weight in pregnancies with clinically suspected SGA or LGA fetuses.     

Five-dimensional long bones biometry for estimation of femur length and fetal weight at term compared to two-dimensional ultrasound: a pilot study

Background/objective: This study aimed to evaluate accuracy of five-dimensional long bones (5D LB) compared to two-dimensional ultrasound (2DUS) biometry to predict fetal weight among normal term women.

Methods: Fifty six normal term women were recruited at Ain Shams Maternity Hospital, Egypt from 14 May to 30 November 2015. Fetal weight was estimated by Hadlock’s IV formula using 2DUS and 5D LB. Estimated fetal weights (EFW) by 2DUS and 5D LB were compared with actual birth weights (ABW).

Results: Mean femur length (FL) was 7.07?±?0.73?cm and 6.74?±?0.67?cm by 2DUS and 5D LB (p?=?.02). EFW was 3309.86?±?463.06?g by 2DUS and 3205.46?±?447.85?g by 5D LB (p?=?.25). No statistical difference was observed between ABW and EFW by 2DUS (p?=?.7) or 5D LB (p?=?.45). Positive correlation was found between EFW by 2DUS, 5D LB, and ABW (r?=?0.67 and 0.7; p?p?=?.15).

Conclusions: 2DUS and 5D LB had same accuracy for fetal weight estimation at normal term pregnancy.     

Fetal biometry and fetal weight estimation: JSUM standardization

From the clinical point of view, it is very important to standardize methods of fetal growth evaluation. The standardization committee of fetal measurement of the Japanese Society of Ultrasound in Medicine (JSUM) announced the recommended standard procedure for fetal biometry, calculation of estimated fetal weight (EFW) and their evaluation method. In short, the abdominal circumference (AC) by the ellipse-tracing method should be the standard for the fetal abdominal measurement and the EFW should be calculated by the following formula:

EFW = 1.07 × BPD. + 0.30 × AC × FL,

where BPD is the biparietal diameter and FL the femur length.     

B型超声测量胎儿股骨皮下组织厚度预测胎儿体重

目的探讨应用Ｂ型超声测量胎儿股骨皮下组织厚度预测胎儿出生体重的临床价值。方法应用Ｂ型超声对１７８例胎儿的双顶径、头围、腹围、股骨长、股骨皮下组织厚度进行测量并与新生儿出生体重的关系进行分析。结果股骨皮下组织厚度与新生儿出生体重相关性最好（ｒ＝０．８６０１）,对巨大儿诊断的敏感性为９１％,特异性为９４％,胎儿股骨皮下组织厚度与孕周呈正相关（ｒ＝０．７０７０）。结论应用Ｂ型超声测量胎儿股骨皮下组织厚度预测胎儿出生体重,方法简单、准确,有较好的临床应用价值。     

Maternal weight characteristics influence recurrence of fetal macrosomia in women with normal glucose tolerance

This study examines the relationship between maternal weight characteristics and recurrence of macrosomia in 111 non-diabetic women who delivered a second baby following primiparous delivery of a macrosomic infant (> 4500 g). Recurrence of fetal macrosomia was associated with greater maternal body mass index (P = 0.032), greater initial pregnancy weight (P < 0.05) and total weight gain during second pregnancy (P < 0.01). Women delivering a first macrosomic infant should avoid excessive weight gain before and during a subsequent pregnancy.     

Factors affecting the accuracy of ultrasonographical fetal weight estimation in twin pregnancies

Objective.?To determine the factors affecting the accuracy of ultrasonographic weight estimation in twins.

Methods.?152 sets of twins delivered vaginally, were included. Effects of fetal weights, inter-twin weight discordance, chorionicity, early rupture of membranes, intrauterine growth restriction, and presentations of twins on errors of estimated fetal weights were evaluated. The primary measures of estimated fetal weight accuracy compared were mean-percentage-error and the standart deviation (SD) of percentage errors.

Results.?Mean percentage errors for the first fetus (8.13?±?6.82) and the second fetus (8.07?±?6.88) were similar (p?=?0.64). Random errors of both fetuses were also similar (p?=?0.78). If one of the fetuses had IUGR, the percentage error and also the random error of that fetus would increase significantly. Different presentations and fetal gender combinations were similar for both types of errors of fetal weight estimation. A weak negative lineer relationship was found between the weight of the first fetus and its percentage error (r?=??0.27, p?=?0.04). A similar relation was present between the weight and percentage error of the second fetus (r?=??0.29, p?=?0.03). Percentage errors and also random errors of both fetuses were significantly higher if severe discordance was present between twins (p?=?0.01 and p?=?0.02, respectively).

Conclusions.?IUGR, fetal weights, and inter-twin discordence are the factors affecting the accuracy of weight estimation by ultrasonography.     

Effect of oligohydramnios on the accuracy of sonographic foetal weight estimation in at term pregnancies

Objective

Ultrasound estimation of foetal weight is a very important aspect of antenatal care. The role of amniotic fluid volume as a potential factor which may impede the relevance of ultrasonographic foetal weight estimation is still questionable. The aim of our study was to evaluate the impact of isolated oligohydramnios on the accuracy of ultrasound foetal weight estimation in at term pregnancies when examination was performed within 48 h before delivery.