Abstract: Background: The use of ultrasound for determination of fetal weight spans over three decades now. The correct determination of fetal weight prior to delivery accurately is of utmost importance and greatly influences the clinical management, the outcome of pregnancy, delivery and survival of the new born.
Aim abd Objectives: Objective of this study was to find the relative accuracy of Ultrasound and clinical methods to estimate fetal weight at term in a regional Indian population, to stratify four birth weight groups and to observe which formula performs best in each weight group and lastly to determine the population specific mean birth weight.
Method: This prospective observational study conducted in the hospital attached to Santhiram Medical College included 500 women with term, singleton, vertex pregnancies with no congenital fetal anomalies whose gestational age was accurately determined, who were subjected to an ultrasonographic examination by a single observer within a week of delivery and estimated fetal weight assessed clinically with J&T and Dares formulae and later compared with the actual birth weight measured within 30 minutes of delivery to determine which method is most accurate.
Results: Population specific mean birth weight was 2876g. Weight computation by Ultrasonography is very close to observed birth weight in 47% of cases. It is followed by Dares formulae with 38.3% of cases. Birth weight estimation by J & T has the maximum difference with observed birth weight. The difference between the mean of observed birth weight and predicted birth weight is least when Dares formula is used for estimation. Mean difference between observed birth weight and predicted birth weight by Dares formula is statistically significant with p-value <0.001(<0.05) at 5% significance level. It indicates that the mean of observed birth weight and weight by Dares formula is statistically same. It indicates that the weight estimation by Dares formula is much accurate over other formulae.
Observations: Birth weights of <2.5kg were frequently overestimated and Birth weights of >3.5kg were frequently underestimated. Method with least difference in mean in categories <2.5kg, 2.5-3.0kg and>3.5kg was Ultrasonography and 3.0-3.5kg was J & T.
Conclusion:In conclusion, our study suggests that though ultrasound predicts fetal weight more accurately, Dares method which is also equally good should be used in day to day practice, especially in places where ultrasound is not available.