According to the Centers for Disease Control and Prevention, the rate of cesarean section in the United States rose 6% in 2004, to more than 29%, the highest rate ever recorded; the rate is up more than 40% from that in 1996. Strategies to lower it are being explored, such as encouraging women who undergo a cesarean section to attempt to deliver subsequent babies vaginally. A recent multisite study of 11,587 women who attempted a "vaginal birth after cesarean" (VBAC) revealed that 78% of those who delivered before the estimated due date had a successful vaginal delivery, compared with 69% of women who delivered at 40 weeks or later. After 41 weeks of pregnancy, the rate for successful VBAC decreased to 65%.

Although VBAC was found less likely to be successful as pregnancy lengthened, the relative risk of uterine rupture or of morbidity from any cause was not significantly higher. In all three groups, elective cesarean delivery was associated with a higher risk of morbidity; the highest risk of morbidity was seen with cesarean section after a failed VBAC.

Coassolo KM, et al. Obstet Gynecol 2005; 106(4):700-6.