A comparative study of estimation of fetal weight in term pregnancy by clinical and sonographic method

Birth weight is the critical determinant of neonatal survival, with deviations from the norm increasing the risks of perinatal morbidity and mortality. Accurate estimation of fetal weight is essential for effective management during labor, particularly in high-risk pregnancies. Clinical and sonographic methods are the primary techniques for estimating fetal weight, with each method showing distinct advantages and limitations.

This study aims to compare the accuracy of clinical (Insler's formula) and sonographic (Hadlock's formula) methods in estimating fetal weight, by correlating these estimates with actual birth weight.

A prospective observational study was conducted, including 100 antenatal cases with term singleton pregnancies. Clinical assessments were performed using Insler's formula, while ultrasound-based fetal weight estimation was done using Hadlock's formula. Birth weight was recorded post-delivery, and statistical analysis was performed to assess correlations and agreement.

The mean fetal weight estimated by Insler's formula was 3.23 ± 0.42 kg, and by Hadlock's formula was 3.16 ± 0.44 kg. The actual birth weight averaged 3.06 ± 0.42 kg. Both methods showed fair agreement with actual birth weight, with Cohen's kappa values of 0.274 (Insler's) and 0.167 (Hadlock's), indicating statistically significant agreement in the Insler's formula group (P < 0.001) but not in the Hadlock's formula group (P = 0.089).

Both clinical and sonographic methods demonstrate fair agreement with actual birth weight, but clinical method (Insler's formula) is more accessible, cost-effective, and accurate for fetal weight estimation in low-resource settings. This study suggests that clinical methods can be reliably used in managing labor and delivery in resource-limited environments.