The outcome of delivery of infants weighing more than 4000 g born during two time periods 15 years apart was studied retrospectively. The increased use of cesarean section and other obstetric advances did not reduce the risk of fetal asphyxia and trauma associated with large fetal size. Maternal factors were identified for risk categorization of fetal macrosomia during pregnancy. Macrosomia was rare at 37 weeks and increasingly common thereafter. Fetal size assessment by ultrasound at 36 to 38 weeks' gestation would permit induction of labor for the macrosomic infant before the size became excessive or would make the accoucheur aware of the dangers that may arise during delivery.