Cesarean section rates have risen dramatically in the U.S. over the past 20 years. Although infant mortality has declined during the same period, there is little evidence that more frequent cesarean surgery is the cause. Cesareans save lives or benefit health in certain circumstances, but the incidence of those indications has not increased. Cesarean section also has risks, the most significant for the infant being iatrogenic prematurity or respiratory disease. Maternal mortality is 2-4 times higher and morbidity is 5-10 times higher after a cesarean compared to vaginal birth. The four indications responsible for most of the rise in cesarean rates--previous cesarean, dystocia, breech presentation, and fetal distress--are those conferring the least clear-cut benefit. Demographically, women who are most likely to experience pregnancy complications, low birth weight births, or infant mortality are least likely to have a cesarean. Social, economic, and other factors seem to have a greater influence on the decision to perform a cesarean than does expected medical benefit. The development of neonatal intensive care, expanded access to prenatal care, and greater availability of abortion and family planning have contributed more to falling infant mortality. It has been estimated that approximately half the cesareans currently performed in the U.S. are medically unnecessary, resulting in considerable avoidable maternal mortality and morbidity, and a cost of over $1 billion each year.