Correlation between ultrasound estimated fetal weight in term pregnancy and actual birth weight amongst pregnant women in Jos

Abstract

Background: High rate of perinatal mortality is still a major cause for concern in developing countries such as Nigeria. A large portion of this problem is related to birth-weight which remains the single most important parameter that determines neonatal survival. A simple and accurate method of estimating intrauterine fetal
weight that can be easily applied to all pregnancies is thus an important means of reducing perinatal mortality and morbidity.

Objective: To determine the correlation between ultrasound estimated fetal weight in term pregnancy and actual birth weight amongst pregnant women in Jos, North-Central Nigeria

Methods: This research was a prospective cross-sectional hospital based study correlating sonographic estimated fetal weight at term with actual birth weight in Jos, North-Central Nigeria. Ultrasound estimated fetal weight was calculated using a combination of the biparietal diameter (BPD), abdominal circumference (AC), and femoral length (FL) usingHadlock formula, inbuilt in ALOKA SSD-4000 ultrasound machine fitted with 3.5MHz curvilinear transducer.

Results: A total of 400 women were recruited for the study. The mean maternal age was 29.35 years, and the mean gestational age at delivery was 38 weeks and 6 days. The mean actual birth weight was 3209.31 ± 497.52g while the mean ultrasound estimated fetal weight was 3177.85 ± 533.01g.There was an overall strong correlation between ultrasound estimated fetal weight and actual birth weight (r=0.835) and the difference was not statistically significant (p>0.001.). Also, 75% of the estimates were within 10% of the actual birth weight.

Conclusion: Ultrasound estimated fetal weight correlated strongly with actual birth weight especially for babies with normal birth weight. However, for babies at the extremes of birth weight, ultrasound estimated fetal weight would need to be correlated with physical examination (including clinical estimation) to avoid unnecessary obstetric intervention.

Keywords: Correlation, ultrasound, fetal weight, actual weight, term pregnancy