Abstract
Fewer women today are attempting vaginal delivery after a previous cesarean delivery, mostly because of concern about its safety. This prospective cohort study, carried out at 19 academic medical centers, compared outcomes in 17,898 women with a history of cesarean section who attempted vaginal delivery and 15,801 others who had elective repeat cesarean section without labor. Women having a trial of labor were more likely than those having elective repeat cesarean delivery to be less than 30 years of age, black, unmarried, and nonobese. They also were likelier to have both preterm and delayed delivery.Vaginal delivery succeeded in 73.4% of women. The rate of symptomatic uterine rupture in women having a trial of labor was 0.7%. It was the same for those having a previous low transverse incision and 2.0% in those with a previous low vertical incision. Uterine rupture was associated with augmentation of labor using oxytocin and also with induction of labor by any method. Both endometritis and maternal blood transfusion were significantly more frequent with a trial of labor. Hysterectomy was performed in 88 women, in 41 after a trial of labor. The odds ratio for maternal adverse events in women having a trial of labor was 1.96 (95% confidence interval, 1.73–2.22) after adjusting for demographic differences and maternal diseases. Hypoxic–ischemic encephalopathy was significantly more frequent when women had a trial of labor at term than in the infants of women having elective repeat cesarean delivery. Both stillbirths and neonatal deaths were more frequent in the trial of labor group. There were no intrapartum fetal deaths.Adverse perinatal outcomes are more frequent when women with a history of cesarean delivery who undergo a trial of labor. Maternal adverse events also are increased. Although the degree of risk is small, it is important that both pregnant women and the healthcare providers who advise them be aware of the possible consequences.