Ultrasonic diagnosis of altered fetal growth by use of a normal ultrasonic fetal weight curve.

A previously developed normal ultrasonic fetal weight curve was used for antenatal diagnosis of altered fetal growth in 595 patients who had undergone real-time ultrasound examination within 72 hours before birth. Fetal weight was estimated using biparietal diameter and abdominal circumference and plotted on the normal curve. The diagnosis of small for gestational age (SGA) or large for gestational age (LGA) was based on whether the ultrasonic weight fell below or above the normal limits. After delivery, infants were classified as SGA, LGA, or average for gestational age (AGA) by birth weight, and the postnatal diagnosis was compared to the antenatal ultrasound diagnosis. The sensitivity of the technique for the diagnosis of SGA infants was 89.9%; for LGA it was 73.5%. The overall specificity of the technique was 79.8%.