Induction at 41 weeks increases the risk of caesarean section in a hospital with a low rate of caesarean sections

Objective: To analyse the impact of a change in the management of prolonged pregnancies from inducing labour at 42(+0) to induction at 41(0-6). Design: Retrospective cohort study. Methods: Analysis of 3563 single pregnancies with cephalic presentation of >= 41 weeks of gestation delivered in Cruces University Hospital (Spain). Two cohorts were compared corresponding to before and after the change in the policy on induction. Main outcome measures: Induction rate, vaginal delivery rate, newborn morbidity and mortality. Results: The overall rate of caesarean sections in the patients included in the study was 12.8% (19.5% among those induced and 8.4% among those in whom the onset of labour has been spontaneous). The caesarean section rate in cohorts 41(0-6) and 42(+0) were 14.1% and 11.4%, respectively (p = 0.01). Though there were more newborns with umbilical cord blood ph<7.10 in cohort 41(0-6) than in the other group (8.7% versus 4.5%; p < 0.01), no significant differences were found between cohorts in 5-min Apgar score < 7, number of admissions to the neonatal care unit or perinatal mortality. Conclusion: The induction of labour during week 41 in prolonged pregnancies may increase the rate of caesarean sections in hospitals with low rates of caesarean sections.