• Caesarean section;
  • cohort study;
  • infant mortality;
  • Sweden;
  • uterine rupture;
  • vaginal birth after caesarean

Objective  Uterine rupture is a rare but a catastrophic event. The aim of the present study was to explore the risk factors for uterine rupture and associated neonatal morbidity and mortality among a cohort of Swedish women attempting vaginal birth in their second delivery.

Design  Population-based cohort study.

Setting  Sweden.

Population  A total of 300 200 Swedish women delivering two single consecutive births between 1983 and 2001.

Methods  Swedish population-based registers were used to obtain information concerning demographics, pregnancy and birth characteristics, and neonatal outcomes. Logistic regression was used to analyse potential risk factors for uterine rupture and risk of neonatal mortality associated with uterine rupture. Odds ratios were used to estimate relative risks using 95% CI.

Main outcome measure  Uterine rupture and neonatal mortality in the second pregnancy.

Results  Compared with women who delivered vaginally in their first birth, women who underwent a caesarean delivery were, during their second delivery, at increased risk of uterine rupture (adjusted OR 41.79; 95% CI 29.73–57.00). Induction of labour, high (≥4000 g) birthweight, postterm (≥42 weeks) births, high (≥35 years) maternal age, and short (≤164 cm) maternal stature were also associated with increased risk of uterine rupture. Uterine rupture was associated with a substantially increased risk in neonatal mortality (adjusted OR 65.62; 95% CI 32.60–132.08).

Conclusion  The risk of uterine rupture in subsequent deliveries is not only markedly increased among women with a previous caesarean delivery but also influenced by induction of labour, birthweight, gestational age, and maternal characteristics.