Accuracy of Fetal Weight Estimation in Women with Diet Controlled Gestational Diabetes

Prediction of birth weight in pregnancy with gestational diabetes mellitus using an artificial neural network

Gestational diabetes mellitus (GDM) is common during pregnancy, with the prevalence reaching as high as 31.0% in some European regions (McIntyre et al., 2019). Dysfunction of the glucose metabolism in pregnancy can influence fetal growth via alteration of the intrauterine environment, resulting in an increased risk of abnormal offspring birth weight (McIntyre et al., 2019). Infants with abnormal birth weight will be faced with increased risks of neonatal complications in the perinatal period and chronic non-communicable diseases in childhood and adulthood (Mitanchez et al., 2015; McIntyre et al., 2019). Therefore, accurate estimation of birth weight for neonates from women with GDM is crucial for more sensible perinatal decision-making and improvement of perinatal outcomes. Timely antenatal intervention, with reference to accurately estimated fetal weight, may also decrease the risks of adverse long-term diseases.

The effect of fetal weight on the accuracy of sonographic weight estimation among women with diabetes

Objective: The assessment of sonographic estimated fetal weight (EFW) enables identification of fetuses in the extremes of weight, thus aiding in the planning and management of peripartum care. There are conflicting reports regarding the accuracy of EFW in diabetic mothers. We aimed to study the factors associated with the accuracy of EFW at term, specifically the role of gestational and pre-gestational diabetes in this setting.Methods: A retrospective study including all women carrying singleton term gestations who delivered within a week following a sonographic fetal weight estimation between 2011 and 2019. Accurate EFW was defined as within 10% of the actual birthweight. We allocated the study cohort into two groups: (1) Accurate EFW (2) inaccurate EFW. Both groups were compared in order to identify factors associated with the inaccuracy of EFW.Results: Overall, 41,263 deliveries were available for evaluation, including 412 (1.0%) deliveries among women with pre-gestational diabetes and 4,735 (11.5%) among women with gestational diabetes. Of them, 7,280 (17.6%) had inaccurate EFW. Inaccurate EFW was associated with nulliparity, OR 0.82 [95% CI] (0.78-0.87), oligohydramnios, OR 0.81 [95% CI] (0.71-0.93), pregestational diabetes, OR [95% CI] 0.61 (0.50-0.79), and extremity of fetal weight; <2,500 grams-OR [95% CI] 0.37 (0.33-0.41) and >4,000 grams OR [95% CI] 0.52 (0.48-0.57). On multiple regression analysis, the following factors were independently associated with inaccurate EFW: pregestational diabetes, OR [95% CI] 0.58 (0.46-0.73), p < .001, nulliparity, OR [95% CI] 0.86 (0.82-0.91), p < .001 and higher fetal weight (for each 500 grams), OR [95% CI [1.25 (1.21-1.30), p < .001. On analysis of different weight categories, pregestational diabetes was associated with inaccurate EFW only in those with birthweight >3,500 grams, OR [95% CI] 0.37 (0.24-0.56) (p < .001).Conclusion: Among pregestational diabetic women, the accuracy of sonographic EFW when assessed to be >3,500 grams is questionable. This should be taken into consideration when consulting women and planning delivery management.Synopsis: Among pregestational diabetic women, the accuracy of estimated sonographic fetal weight higher than 3,500 grams is of limited accuracy.

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.

Sonographic prediction of macrosomia in pregnancies complicated by maternal diabetes: finding the best formula

PURPOSE

To evaluate the best performing formula for macrosomia prediction in pregnancies complicated by diabetes.

METHODS

A retrospective analysis was performed of 1060 sonographic fetal biometrical measurements performed within 7 days of delivery in term pregnancies (37-42 gestational weeks) complicated by diabetes. Sonographic prediction of macrosomia (≥ 4000, ≥ 4250, and ≥ 4500 g) was evaluated utilizing ten previously published formulas by: (1) calculating for each macrosomia threshold the sensitivity, specificity, positive and negative predictive value, and ± likelihood ratio for macrosomia prediction; (2) comparing the systematic and random error and the proportion of estimates < 10% of birth weights between macrosomic and non-macrosomic neonates. Best performing formula was determined based on Euclidean distance.

RESULTS

97 (9.2%) macrosomic neonates (> 4000 g) were included. Median birth weight was 3380 (1866-3998) g for non-macrosomic and 4198 (4000-5180) g for macrosomic neonates. Higher macrosomia cutoff was associated with higher specificity and lower sensitivity. We found a considerable variation between formulas in different accuracy parameters. Hadlock's formula (1985), based on abdominal circumference, femur length, head circumference and biparietal diameter, had the shortest Euclidean distance, reflecting the highest accuracy.

CONCLUSION

Prediction of macrosomia among women with diabetes differs significantly between formulas. In our cohort, the best performing formula for macrosomia prediction was Hadlock's formula (1985).

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.

Sonographic weight estimation in fetuses with breech presentation

PURPOSE

To assess the accuracy of weight estimation (WE) in fetuses with breech presentation and to compare it directly with a control group of fetuses in vertex presentation.

MATERIALS AND METHODS

In a retrospective cohort study, the accuracy of WE in fetuses with breech presentation (n = 244) was evaluated using eight sonographic models and was compared with a control group of fetuses in vertex presentation (n = 244). Each fetus underwent ultrasound examination with complete biometric parameters within 7 days before delivery. The accuracy of the different formulas was compared using means of percentage error (MPE), a measure that reflects systematic error; standard deviation values of MPEs, a measure for random error; medians of absolute percentage error (MAPE), which take both the systematic and random error into account and the percentage of fetal WEs falling within a 10 % range of the actual birth weight.

RESULTS

Significantly lower (more negative) MPE values were found in the breech group with the Hadlock (AC, FL) formula, whereas no significant differences were seen with any of the other equations. When compared to zero, in the breech group, a significant systematic error was found with five formulas, while in the control group a significant systematic error was found with three equations. With regard to random error and MAPE, no significant differences were found between the two groups, irrespective of the formula applied. Generally, in both groups, formulas based on three or four biometric indices were more accurate in detecting fetal weight than formulas with only one or two parameters.

CONCLUSIONS

Weight estimation in fetuses with breech presentation was as accurate as weight estimation in fetuses with vertex presentation. Using the currently available, well-established formulas should therefore also be appropriate for WE in fetuses with such malpresentations.