An evaluation of two methods of antenatal ultrasonic fetal weight estimation

The accuracy of 2 methods of antenatal ultrasonic fetal weight estimation has been compared. The method of Warsof et al. (1977) computes the estimated fetal weight from measurements of the abdominal circumference and the biparietal diameter, whilst the method of Higginbottom et al. (1975) utilises the circumference of the abdomen alone. The estimated weights obtained by the 2 methods were compared with the actual weights at birth occurring within 48 hours of the estimation. Using the tables of Warsof et al., 77% of the actual birth weights were within 10% of the estimated weight, with a coefficient of correlation of 0.95. Eighty-two per cent of babies less than 2,500 g fell within 10% of the estimated weight (Warsof et al.), with a coefficient of correlation of 0.96. Using the formula of Higginbottom et al., 56% of the total birth weights fell within 10% of the estimated weight and the coefficient of correlation was 0.89. Forty-five per cent. of the babies weighing less than 2,500 g were within the 10% range, the coefficient of correlation of this subgroup being 0.91. It is concluded that antenatal fetal weight estimation using the computed tables of Warsof et al. is superior in our population to the method described by Higginbottom et al., and such antenatal fetal weight estimation is of potential value in many high risk pregnancies.