Risk of stillbirth after a previous caesarean delivery: A Swedish nationwide cohort study.

ABSTRACT

OBJECTIVES: To investigate the risk of stillbirth in relation to (1) a previous caesarean delivery (CD) compared with those following a vaginal birth (VB); and (2) vaginal birth after caesarean (VBAC) compared with a repeat CD. DESIGN: Population-based cohort study. SETTING: The Swedish Medical Birth registry. POPULATION Women with their first and second singletons between 1982 and 2012. METHODS: Multivariable logistic regression models were performed to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI) of the association between CD in the first pregnancy and stillbirth in the second pregnancy and the association between VBAC and stillbirth. Sub-group analyses were performed by types of CD and timing of stillbirth (antepartum and intrapartum). MAIN OUTCOME MEASURES: Stillbirth (antepartum and intrapartum fetal death). RESULTS: Of the 1 771 700 singleton births from 885 850 women, 117 114 (13.2%) women had a CD in the first pregnancy, and 51 755 had VBAC in the second pregnancy. We found a 37% increased odds of stillbirth (aOR 1.37; 95% CI 1.23-1.52) in women with a previous CD compared with VB. The odds of intrapartum stillbirth were higher in the previous pre-labour CD group (aOR 2.72; 95% CI 1.51-4.91) and in the previous in-labour CD group (aOR 1.35; 95% CI 0.76-2.40), although not statistically significant in the latter case. No increased odds were found for intrapartum stillbirth in women who had VBAC (aOR 0.99; 95% CI 0.48-2.06) compared with women who had a repeat CD. CONCLUSIONS: This study confirms that a CD is associated with an increased risk of subsequent stillbirth, with a greater risk among pre-labour CD. This association is not solely mediated by increases in intrapartum asphyxia, uterine rupture or attempted VBAC. Further research is needed to understand this association, but these findings might help healthcare providers to reach optimal decisions regarding mode of birth, particularly when CD is unnecessary.