Delivery after previous cesarean: a risk evaluation. Swiss Working Group of Obstetric and Gynecologic Institutions

To examine the risks of vaginal delivery after previous cesarean and to find criteria to help decide whether a trial of labor or an elective repeat cesarean should be preferred.

We evaluated 29,046 deliveries after previous cesarean registered in a pooled database of 457,825 deliveries used to assess quality control in gynecology and obstetrics departments in Switzerland.

Among the 17,613 trial-of-labor cases logged (attempt rate 60.64%), the success rate was 73.73% (65.56% after inducing labor and 75.06% after the spontaneous onset of labor). The following complications were significantly more frequent in the previous-cesarean group: maternal febrile episodes (relative risk [RR] 2.77; 95% confidence interval [CI] 2.52, 3.05), thromboembolic events (RR 2.81; CI 2.23, 3.55), bleeding due to placenta previa during pregnancy (RR 2.06; CI 1.70, 2.49), uterine rupture (92 cases; RR 42.18; CI 31.09, 57.24), and perinatal mortality (118 cases, including six associated with uterine rupture; RR 1.33; CI 1.10, 1.62). The postcesarean group also showed a 0.28% rate of peripartum hysterectomy (81 cases; RR 6.07; CI 4.71, 7.83). There was one maternal death in the group, compared with 14 maternal deaths in the group without previous cesarean (no statistical significance). The risk of uterine rupture for patients with previous cesareans was elevated in the trial-of-labor group compared with the group without trial of labor (RR 2.07; CI 1.29, 3.30), but all other maternal risks, including peripartum hysterectomy (RR 0.36; CI 0.23, 0.56), were lower. When comparing the women having a trial of labor, the 70 with uterine rupture more often had induced labor (24.29% compared with 13.92% in the nonrupture group; P = .013), had epidural anesthesia (24.29% compared with 8.44%; P < .001), had an abnormal fetal heart rate tracing (32.86% compared with 8.53%; P < .001), and had failure to progress (21.43% compared with 7.98%; P = .001).

A history of cesarean delivery significantly elevates the risks for mother and child in future deliveries. Nonetheless, a trial of labor after previous cesarean is safe. Induction of labor, epidural anesthesia, failure to progress, and abnormal fetal heart rate pattern are all associated with failure of a trial of labor and uterine rupture.