Estimated fetal weight: applicability to small- and large-for-gestational-age fetus

Ultrasonic formulas using femur length and abdominal circumference with or without biparietal diameter were found to be highly accurate in predicting the weight of normal-sized term infants. The small-for-gestational age fetus, however, was overestimated and the large-for-gestational-age fetus was underestimated. The fetal weight formulas tested that were appropriate for the entire study group were not applicable to those fetuses having altered growth.