Risk of uterine rupture during labor among women with a prior cesarean delivery.

Background: Each year in the United States, approximately 60 percent of wom en with a prior cesarean delivery who become pregnant again attempt labor. Concern persists that a trial of labor may increase the risk of uterine rup ture, an uncommon but serious obstetrical complication. Methods: We conducted a population-based, retrospective cohort analysis usi ng data from all primiparous women who gave birth to live singleton infants by cesarean section in civilian hospitals in Washington State from 1987 th rough 1996 and who delivered a second singleton child during the same perio d (a total of 20,095 women). We assessed the risk of uterine rupture for de liveries with spontaneous onset of labor, those with labor induced by prost aglandins, and those in which labor was induced by other means; these three groups of deliveries were compared with repeated cesarean delivery without labor. Results: Uterine rupture occurred at a rate of 1.6 per 1000 among women wit h repeated cesarean delivery without labor (11 women), 5.2 per 1000 among w omen with spontaneous onset of labor (56 women), 7.7 per 1000 among women w hose labor was induced without prostaglandins (15 women), and 24.5 per 1000 among women with prostaglandin-induced labor (9 women). As compared with t he risk in women with repeated cesarean delivery without labor, uterine rup ture was more likely among women with spontaneous onset of labor (relative risk, 3.3; 95 percent confidence interval, 1.8 to 6.0), induction of labor without prostaglandins (relative risk, 4.9; 95 percent confidence interval, 2.4 to 9.7), and induction with prostaglandins (relative risk, 15.6; 95 pe rcent confidence interval, 8.1 to 30.0). Conclusions: For women with one prior cesarean delivery, the risk of uterin e rupture is higher among those whose labor is induced than among those wit h repeated cesarean delivery without labor. Labor induced with a prostaglan din confers the highest risk. (N Engl J Med 2001;345:3-8.) Copyright (C) 20 01 Massachusetts Medical Society.