Does sweeping of membranes beyond 40 weeks reduce the need for formal induction of labour?

Objective To assess the efficacy of sweeping of membranes beyond 40 weeks of gestation in reducing the incidence of induction of labour, when induction was planned at 42 weeks. Design Prospective randomised controlled trial. Setting A regional obstetric unit in Hong Kong. Population and methods A total of 120 women with certain gestational age, determined by early pregnancy ultrasound scan, were recruited from 1st July, 1998 to 31st December, 1999. Sixty women were randomly allocated to sweeping of membranes and the other 60 women acted as control. The satisfaction for women allocated to sweeping of membranes was assessed by a questionnaire after the procedure. The two groups were assessed on intention-to-treat basis. Main outcome measures The incidence of formal induction of labour was compared between the two groups. Possible complications of sweeping of membranes such as rupture of membranes, intrapartum infection, postpartum infection, and neonatal infection were also assessed. Maternal and perinatal outcomes were also assessed. Results The recruitment to delivery interval was significantly shorter among women who had sweeping of membranes (3.2 versus 4.2 days, P < 0.05). The incidence of induction of labour was comparable (35.5% versus 38%, RR 0.91, 95% Cl 0.57-1.46). The incidences of caesarean section and assisted vaginal delivery were comparable. The incidences of premature rupture of membranes, intrapartum, and postpartum infection were comparable. The perinatal outcomes were also comparable between the two groups. Up to 70% of women found that this procedure was associated with significant discomfort. One third of these women complained of significant pain. Conclusions Sweeping of membranes beyond 40 weeks does not reduce the need for formal induction of labour at 42 weeks. Although it is safe, the majority of women felt uncomfortable during the procedure.