Accuracy of Ultrasound in Estimating Fetal Weight at Term

Abstract
Background: To compare the accuracy of different sono-graphic formulae for fetal weight estimation at term.
Material and Methods: Comparative cross-sectional study to evaluate 8 different formulae using 300 sonographic weight estimations performed within 24 hours before delivery. Using correlation coefficient, regression analysis and Bland and Altman method, to compare between the studied formulae with each other and knowing the effect the different fetal biometric indices on accuracy of estimates by ultrasound.
Results: A considerable variation in the accuracy of the different formulae was found. For Birth Weights (BWs) in the range of 2500 to 3500g, formulae based on 3 or 4 fetal biometric indices were significantly more accurate than formulae that incorporated only 1 or 2 indices. The accuracy of formulae decreased at the extreme of birth weight >_4000gs, leading to underestimation of ABW (actual birth weight).
Conclusion: We conclude that to improve the accuracy of fetal weight estimation, sonographic formulae that are based on 3 or 4 fetal biometric indices should be preferred.