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 CD compared to those following a vaginal birth (VB);
and 2) vaginal birth after caesarean (VBAC) compared to 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 to VB.
The odds of intrapartum stillbirth was higher in previous pre-labour CD
group (aOR:2.72 [95% CI, 1.51–4.91]) than 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 was
found for intrapartum stillbirth in women who had VBAC (aOR:0.99 [95%
CI, 0.48–2.06]) compared to women who had a repeat CD, whereas women
with antepartum stillbirth were more likely to have a VBAC (aOR:4.49
[95% CI, 3.55–5.67]). 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 health care providers to
reach optimal decisions regarding mode of birth, particularly when CD is
unnecessary.