Determining the fetal weight accurately is essential for prenatal treatment and decision-making. The purpose of this study was to estimate the weight of the fetus in Ojo, Lagos State, Nigeria between 20 and 40 weeks of gestation by developing a fetal anthropometric model using ultrasound measures. A longitudinal study of 300 pregnant women was conducted, with obstetric ultrasound scans images. Fetal biometric parameters (abdominal circumference and femur length) were measured and correlated to estimate fetal weight using Hadlock’s formula. A predictive model for fetal weight estimation was created using regression analysis. From the results, fetal biometric measurements are connected. When one goes up, the other goes down. This means that there is a relationship between fetal biometric measurements and estimated fetal weight (EFW). Hence, the size of a fetus can help us estimate how much it weighs. This shows that fetal measurements are helpful in predicting fetal weight.