Mode of first delivery and severe maternal complications in the subsequent pregnancy.

INTRODUCTION: Severe obstetric complications increase with the number of previous cesarean deliveries. In the Nordic countries most women have two children. We present the risk of severe obstetric complications at the delivery following a first elective or emergency cesarean and the risk by intended mode of second delivery.

MATERIAL AND METHODS: A two-year population-based data collection of severe maternal complications in women with two deliveries in the Nordic countries (n = 213 518). Denominators were retrieved from the national medical birth registers.

RESULTS: Of 35 450 first cesarean deliveries (17%), 75% were emergency and 25% elective. Severe complications at second delivery were more frequent in women with a first cesarean than with a first vaginal delivery, and rates of abnormally invasive placenta, uterine rupture and severe postpartum hemorrhage were higher after a first elective than after a first emergency cesarean delivery [relative risk (RR) 4.1, 95% confidence intervals (CI) 2.0-8.1; RR 1.8, 95% CI 1.3-2.5; RR 2.3, 95% CI 1.5-3.5, respectively]. A first cesarean was associated with up to 97% of severe complications in the second pregnancy. Induction of labor was associated with an increased risk of uterine rupture and severe hemorrhage.

CONCLUSION: Elective repeat cesarean can prevent complete uterine rupture at the second delivery, whereas the risk of severe obstetric hemorrhage, abnormally invasive placenta and peripartum hysterectomy is unchanged by the intended mode of second delivery in women with a first cesarean. Women with a first elective vs. an emergency cesarean have an increased risk of severe complications in the second pregnancy.