Risk of severe maternal morbidity associated with cesarean delivery and the role of maternal age: a population-based propensity score analysis

Abstract

Background: Short-term maternal complications of cesarean delivery remain uncertain because of confounding by indication. Our objective was to assess whether cesarean delivery is associated with severe acute intra- or postpartum maternal morbidity compared with vaginal delivery, overall and according to the timing of the cesarean.

Methods: We performed a case-control analysis using data from EPIMOMS, a prospective population-based study of deliveries at 22 gestation weeks or later from 6 regions of France in 2012-2013. Cases of intra- or postpartum severe acute maternal morbidity that were not a result of a condition present before delivery were compared with controls randomly selected in a 1/50 ratio. Associations between delivery modes and severe acute maternal morbidity were estimated in a propensity score-matched sample.

Results: Among 182 300 deliveries, we identified 1444 cases and 3464 controls. The proportion of cesarean delivery was significantly higher among cases than controls (36.0% v. 18.2%). In the propensity score-matched analysis, cesarean deliveries were significantly associated with a higher risk of severe acute maternal morbidity (adjusted odds ratio [OR] 1.8, 95% confidence interval [CI] 1.5-2.2). This association increased with maternal age and was particularly marked for women aged 35 years or older (adjusted OR 2.9, 95% CI 1.9-4.4). This increased risk was significant for cesarean deliveries during labour in women of all age groups and for those before labour only in women aged 35 years or older (adjusted OR 5.1, 95% CI 2.3-11.0).

Interpretation: Cesarean delivery is associated with a higher risk of severe acute maternal morbidity than vaginal delivery, particularly in women aged 35 years and older. Clinical decisions regarding delivery mode should account for this excess risk accordingly.

Figure 1:

Flow chart showing selection of cases and controls. Note: GW = gestational week, SAMM = severe acute maternal morbidity.

Figure 2:

Association between cesarean delivery and severe acute intra- or postpartum maternal morbidity by maternal age. Note: CI = confidence interval, OR = odds ratio. *Variables for propensity score: country of birth, living without partner, maternal age, body mass index, smoker, pre-existing medical condition, parity and prior cesarean delivery, previous obstetric hemorrhage, previous gestational hypertensive disorders, multiple pregnancy, in vitro fertilization, gestational hypertensive disorder, anemia in third trimester, breech presentation, large for gestational age (LGA), gestational age at delivery, maternity unit status; adjusted for no prophylactic oxytocin after birth; after multiple imputation.†118 women with cesarean delivery matched with 118 women with vaginal delivery. ‡Adjusted for country of birth, living without partner, age, body mass index, smoker, pre-existing medical condition, parity and prior cesarean delivery, previous obstetric hemorrhage, previous gestational hypertensive disorders, multiple pregnancy, in vitro fertilization, gestational hypertensive disorder, anemia in third trimester, breech presentation, no prophylactic oxytocin after birth, LGA, gestational age at delivery, maternity unit status; after multiple imputation. §225 women with cesarean delivery matched with 225 women with vaginal delivery. ¶298 women with cesarean delivery matched with 298 women with vaginal delivery.**226 women with cesarean delivery matched with 226 women with vaginal delivery.

Figure 3:

Association between cesarean delivery (A) before and (B) during labour, and severe acute intra- or postpartum maternal morbidity by maternal age. Note: CI = confidence interval, OR = odds ratio. *Variables for propensity score: country of birth, living without partner, age, body mass index (BMI), current smoker, pre-existing medical condition, parity and prior cesarean delivery, previous obstetric hemorrhage, previous gestational hypertensive disorders, multiple pregnancy, in vitro fertilization, gestational hypertensive disorder, anemia in third trimester, breech presentation, large for gestational age (LGA), gestational age at delivery and maternity unit status; adjusted for no prophylactic oxytocin after birth; after multiple imputation. †Adjusted for country of birth, living without partner, age, BMI, current smoker, pre-existing medical condition, parity and prior cesarean delivery, previous obstetric hemorrhage, previous gestational hypertensive disorders, multiple pregnancy, in vitro fertilization, gestational hypertensive disorder, anemia in third trimester, breech presentation, no prophylactic oxytocin after birth, LGA, gestational age at delivery and maternity unit status; after multiple imputation.