Use of the fetal chest in estimating fetal weight.

Abstract

This study was designed to develop formulas using the chest circumference instead of the abdominal circumference for estimating fetal weight. Ultrasonographic measurements of the chest circumference, biparietal diameter, abdominal circumference, humeral length, and femoral length were obtained in 75 term fetuses of uncomplicated pregnancies within 24 hours of delivery. Three equations for fetal weight estimation that used the chest circumference, instead of the abdominal circumference, in combination with the biparietal diameter or the humeral length were developed by regression analysis. The average mean errors of fetal weight estimation for these equations vary from 7.1% to 7.6%. These equations may be used in predicting the birth weight when the fetal abdomen is altered by certain fetal abnormalities.