Comparative study of clinical assessment of fetal weight estimation using Johnson’s formula and ultrasonographic assessment using Handlock’s formula at or near term and its correlation with its actual birth weight

Abstract

Background: Fetal growth assessment is an important part of antenatal care. Accurate estimation of fetal weight is one of the important aspects in management of labour. Estimation of birth weight by Johnson’s formula based on symphysiofundal height has advantage of speed, economy and general applicability. Obstetric ultrasound can predict fetal weight with a great degree of precision.

Methods: The prospective study was conducted at the Department of Obstetrics and Gyenecology, Yenepoya Medical College and Hospital, Mangalore on 100 pregnant women at or near term. Detailed history was taken, general, obstetric and systemic examination was done. Pelvic examination also done. Estimated fetal weight calculated using Johnson’s formula clinically and ultrasound was done to calculate estimated fetal weight using Handlock’s formula and correlated the birth weight calculated by two methods with its actual birth weight. Then the statistical analysis done to estimate the accuracy of two methods in estimated fetal weight.

Results: In this study, out of 100 pregnant women, mean actual birth weight was 3041.6gms. Actual birth weight divided into 3 groups 14% birth weight <2.5kg, 73% had 2.5-3.5kg and 13% had >3.5kg. Accuracy of both methods evaluated, ultrasonographic measurement more accurate than clinical estimation but the error with Johnson’s formula was with low birth babies.

Conclusions: Estimated fetal weight using Ultrasonographic Handlock’s formula was more accurate than Johnson’s formula. However, the results of Johnson’s formula were comparable to Handlock’s.