Pregnancy outcome following ultrasound diagnosis of macrosomia.

Both elective cesarean and early induction have been proposed for pregnancies in which the fetus is suspected to be macrosomic by ultrasound examination. We studied 242 nondiabetic women with estimated fetal weights (EFWs) by ultrasound of at least 4000 g or the 90th percentile for gestational age at 36 or more weeks' gestation. In 66 of 86 women (77%) delivering within 3 days of ultrasound examination, EFW exceeded birth weight. In only 41 of these 86 women (48%) were the EFWs within the corresponding 500-g category of birth weight. A trial of labor resulted in vaginal delivery in 76 of 106 women (72%). There were five cases of shoulder dystocia but no birth trauma. Estimated fetal weights and birth weights were not significantly different between the women who had a trial of labor and those who did not. Our results do not support cesarean delivery or early induction as a means of preventing infant morbidity when fetal macrosomia (weight of 4000 g or more or the 90th percentile for gestational age) is diagnosed by ultrasound.