Estimation of fetal weight in term singleton pregnancy by various clinical methods and its correlation with actual birth weight

This study was undertaken to evaluate the accuracy of various clinical methods for fetal weight estimation in comparison with the actual birth weight and secondarily compare the accuracy with ultrasound-based Hadlock’s formula, given the critical role of fetal weight in obstetric decision-making and the limited availability of ultrasound in resource-constrained settings. A prospective observational study was conducted on 385 term singleton pregnancies (37–40 weeks) with cephalic presentation and no complicating fetal or maternal conditions. Estimated fetal weights were calculated using Johnson’s, Dare’s, and Kongnyuy-Mbu’s clinical formulas, as well as Hadlock’s ultrasound method, and compared with actual birth weight post-delivery.

The actual mean birth weight was 3117.02 ± 323.89 g. Hadlock’s method demonstrated the highest accuracy (mean absolute percentage error [APE]: 5.60 ± 4.97%) and the strongest correlation with actual weight (ICC = 0.72). Among clinical methods, Kongnyuy-Mbu’s formula performed best (APE: 5.89 ± 5.41%, ICC = 0.77), followed by Dare’s and Johnson’s. All methods showed significant correlation with actual birth weight (p < 0.001). Within ±10% of actual birth weight, Kongnyuy-Mbu’s (83.4%) and Hadlock’s (83.1%) methods were most accurate. Bland-Altman analysis confirmed good agreement across all methods.

The findings affirm that while ultrasound remains the gold standard, clinical methods—especially Kongnyuy-Mbu’s—can serve as reliable and practical alternatives in settings lacking ultrasound access, offering substantial clinical utility for fetal weight estimation in routine antenatal care.