Investigating the Accuracy of Ultrasound Imaging in Measuring Fetal Weight in Comparison with the Actual Postpartum Weight

Abstract

Background: Antenatal ultrasonography measurements of the estimated fetal weight (EFW) are a critical point in the decision-making process of obstetric planning and management to preserve the safety of both the newborn and the mother. This study aims to investigate the accuracy of ultrasonography to measure the EFW in comparison with the actual birth weight (BW) measured immediately after delivery. Methods: In this retrospective study, electronic records of 270 newborns who fulfilled the inclusion criteria were retrieved. A structured data sheet was used to collect the EFW, calculated by the Hadlock A formula using real-time ultrasound imaging on the day of delivery or the day before, and the actual BW immediately after delivery. Results: Out of 270 fetuses, 53.7% (145) were female, and 46.3% (125) were male. The mean BW was 2918.1 ± 652.81 g (range: 880 to 5100). The mean EFW was 3271.55 ± 691.47 g (range: 951 to 4942). The mean gestational age was 38 ± 2.48 weeks (range: 29 to 42). Spearman’s rho correlation test revealed strong compatibility between EFW and BW (r = 0.82, p < 0.001). Linear regression analysis showed a strong correlation between EFW and BW (R = 0.875, R2 = 0.766, and p < 0.001). The cross-tabulation test showed 86.8%, 78.4%, and 26.9% compatibility between measurements of EFW and the true BW in group-1 (<2500 g), group-2 (2500–4000 g), and group-3 (>4000 g) fetuses (p< 0.001). Conclusions: EFW using ultrasonography yields high compatibility with the actual BW. Despite the slight overestimation, ultrasonography provides high clinical value in obstetric assessment and subsequent management.