Elective induction of labour increases caesarean section rate in low risk multiparous women.

The aim of this study was to compare the risk of secondary caesarean section in induced versus spontaneous labour in the second delivery of low risk women who had a vaginal delivery in their first pregnancy. The data were retrospective cohort from an existing regional database, comparing term (between 37 and 42 gestational weeks) second deliveries in cephalic position in women who had previously given vaginal birth. Diabetes, hypertension and multiple pregnancy were excluded as were those with a birth weight less than 2500 g or more than 4500 g. The difference was not significant when induction was performed after 41 weeks. The results showed a total number of 29693 deliveries were included, 21243 in spontaneous labour and 8450 after induction of labour. In the spontaneous group 312 (1.5%) underwent secondary caesarean section, as compared to 237 (2.8%) in the induced group, p < 0.001, OR 1.93 (95% confidence interval 1.63-2.29). It was concluded that elective induction of labour in low risk women who have previously given vaginal birth is associated with an almost doubled rate of secondary caesarean section if performed before 41 weeks.