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.