Sweeping the membranes: a valid procedure in stimulating the onset of labour?

OBJECTIVE: To determine whether sweeping the membranes in pregnancies of longer than 40 weeks gestation results in an accelerated onset of labour and a reduction in the incidence of induction of labour. DESIGN: A prospective randomised controlled study. SETTING: The antenatal clinic of a district general hospital. SUBJECTS: One hundred and ninety-five antenatal women with pregnancies proceeding beyond 40 weeks gestation. INTERVENTIONS: A Bishop score assessment of the cervix alone or combined with a membrane sweep, on a randomised basis. OUTCOME MEASURES: Subsequent duration of pregnancy to the onset of spontaneous labour. The incidence of induction of labour for post-maturity. RESULTS: Sweeping the membranes significantly reduces the subsequent duration of pregnancy, from an average of five days to two days following the procedure. The proportion of inductions of labour was 8.1% in the swept group and 18.8% in the control group. No harmful side effects to the procedure were noted. CONCLUSIONS: Sweeping the membranes is a safe and useful procedure which results in a reduced incidence of post-mature pregnancies, and a subsequent reduction in the labour induction rate.