Fetal macrosomia, commonly defined as a birth weight of ≥4,000 g irrespective of gestational age, is a major obstetric concern because of its association with increased maternal and neonatal morbidity. Accurate antenatal estimation of fetal weight is therefore essential for appropriate obstetric management and improved pregnancy outcomes. Although ultrasonography is widely regarded as the standard method for fetal weight estimation, its limited availability in resource-constrained settings makes clinical methods attractive alternatives. However, the most accurate method for predicting fetal macrosomia among Nigerian women remains uncertain.

Objective: To compare the accuracy of clinical and sonographic methods of fetal weight estimation in predicting fetal macrosomia among term pregnant women attending Irrua Specialist Teaching Hospital, Nigeria.

Methods: A prospective comparative study was conducted among 300 women with singleton term pregnancies (37–42 weeks' gestation) attending the Department of Obstetrics and Gynaecology, Irrua Specialist Teaching Hospital, Edo State, Nigeria, following informed consent. Data was analysed using IBM SPSS version 20. Descriptive statistics were used to summarise the data, while Student's t-test and Chi-square test were used to compare fetal weight estimation methods. Diagnostic performance was assessed using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), with statistical significance set at p < 0.05.

Results: The AG × SFH method demonstrated the highest diagnostic accuracy for predicting fetal macrosomia, with no significant difference between estimated fetal weight and actual birth weight (p = 0.746), a sensitivity of 76.9%, and a specificity of 97.0%. Similarly, the combined clinical method showed no significant difference from actual birth weight (p = 0.642). In contrast, Johnson's formula, the 10% BMI method, and ultrasonography differed significantly from actual birth weight (p < 0.05), while ultrasonography demonstrated relatively low sensitivity (26.9%) for detecting fetal macrosomia.