Cesarean Delivery

Until 1970 cesarean births accounted for fewer than one in twenty births in the United States. The reason cesarean births were performed was largely for conditions that threatened the life of the mother. These conditions included uterine hemorrhage, hypertension of pregnancy, tuberculosis, diabetes, heart disease, and prolonged labor caused by disproportion between the size of the infant and the size of the birth canal. A small proportion of the cesarean births were performed because the baby (fetus) was in danger of hypoxia (lack of oxygen) as when the umbilical cord slips out of its normal position. Also, some cesarean deliveries were performed as repeat cesarean births for women who had a previous baby by cesarean, because it was believed that once a cesarean had been performed, all subsequent births should be by cesarean delivery.

In the early 1970s, electronic means of continuously monitoring a baby's heart rate during labor became available, and intensive care for newborns was beginning to result in dramatic improvements in the survival of seriously ill infants. In addition, the frequency of serious maternal complications of cesarean birth had continued to decline. As a result of these improvements in the care of mothers and infants, doctors became more inclined to recommend cesarean delivery in situations where either the mother or infant were at any increased risk of illness or long-term developmental abnormality that might be caused by vaginal birth. For example, before 1970 almost all breech births (in which the buttocks or feet of a baby rather than its head are the first to be born) were by vaginal delivery, but by 1988 almost all such births were by cesarean delivery. The increase in the use of cesarean delivery to prevent harm to the fetus from labor and vaginal delivery accounted for the increase in the cesarean birthrate from 5 percent of live births in 1970 to 25 percent in 1988. After 1988 the rate of cesarean birth began to decline somewhat so that by 1996 it was 21 percent.

One of the common reasons for cesarean birth is repeat cesarean delivery, which accounts for approximately 25 percent of all cesarean births. Women who have had a cesarean delivery are at risk of the uterine incision rupturing during labor. This can result in the death of or the serious injury to the infant and life-threatening hemorrhage and possible need for a hysterectomy for the mother. The risk of uterine rupture depends upon the type of uterine incision. A vertical incision in the uppermost portion of the uterus has a 12 percent risk of rupturing during labor. This type of incision was used commonly in the early part of the twentieth century but now is used only on rare occasions. A woman who has had a cesarean birth by this method should have all subsequent births by cesarean delivery before the onset of labor to avoid a catastrophic rupture of the uterus. A transverse incision in the lower portion of the uterus, which is now the most common method of performing a cesarean delivery, is associated with a 0.5 percent risk of rupture during labor. Most women who had this type of cesarean delivery can safely attempt a trial of labor and vaginal delivery provided that labor occurs where there are facilities for and personnel who can perform an immediate cesarean delivery if signs of uterine rupture occur. The increase in the incidence of vaginal birth after a previous cesarean birth accounted for the gradual decline in the cesarean delivery rate after 1988.