The risk of unexplained antepartum stillbirth in second pregnancies following caesarean section in the first pregnancy.

OBJECTIVE To determine if a previous caesarean section increases the risk of unexplained antepartum stillbirth in second pregnancies. STUDY DESIGN Retrospective cohort study. SETTING Large Canadian perinatal database. POPULATION 158 502 second births. METHODS Data were obtained from a large perinatal database, which supplied data on demographics, pregnancy complications, maternal medical conditions, previous caesarean section and pregnancy outcomes. MAIN OUTCOME MEASURES Total and unexplained stillbirth. RESULTS The antepartum stillbirth rate was 3.0/1000 in the previous caesarean section group compared with 2.7/1000 in the previous vaginal delivery group (P= 0.46). Multivariate logistic regression modelling, including terms for maternal age (polynomial), weight >91 kg, smoking during pregnancy, pre-pregnancy hypertension and diabetes, did not document an association between previous caesarean section and unexplained antepartum stillbirth (OR 1.27, 95% CI 0.92-1.77). CONCLUSION Caesarean section in the first birth does not increase the risk of unexplained antepartum stillbirth in second pregnancies.