Factors Associated with the Accuracy of Sonographic Fetal Weight Estimation: A Study of 1262 Vietnamese Pregnancies

Background/Objectives: Sonographic estimated fetal weight (EFW) guides many obstetric decisions. We examined maternal, fetal and sonographic factors associated with EFW error using the Hadlock II, Hadlock III and Shinozuka formulas.

Methods

This is a retrospective cross-sectional study of 1262 singleton pregnancies at 30–41 weeks scanned within 3 days before delivery. Accuracy was assessed by mean percentage error (MPE), mean absolute percentage error (MAPE), successful estimation rate (SER; error ≤ 10%), Bland–Altman analysis with regression-based limits of agreement and Deming regression. Formulas were compared with paired tests. Each factor’s contribution was measured as the decrease in Nagelkerke R2 (ΔR2) in multivariable logistic regression; factor × formula interactions were tested with generalised estimating equations (GEE).