Fetal macrosomia, arbitrarily defined as a birth weight of more than 4,000 g (8 lb, 13 oz) complicates more than 10 percent of all pregnancies in the United States. It is associated with increased risks of cesarean section and trauma to the birth canal and the fetus. Fetal macrosomia is difficult to predict, and clinical and ultrasonographic estimates of fetal weight are prone to error. Elective cesarean section for suspected macrosomia results in a high number of unnecessary procedures, and early induction of labor to limit fetal growth may result in a substantial increase in the cesarean section rate because of failed inductions. Pregnancies complicated by fetal macrosomia are best managed expectantly. When labor fails to progress as expected, the possibility of fetopelvic disproportion should be considered within the context of the best estimate of the fetal weight.