Randomised controlled trials (RCTs) that compared Foley catheter balloon to locally applied prostaglandins for cervical ripening and induction of labour in women with singleton pregnancies with an unfavourable cervix (defined as a Bishop score of ≤6 at ≥28 weeks gestation) in the third trimester were eligible for inclusion. Additional criteria for included pregnancies were that the live foetus was in vertex presentation and the membranes were intact.
The included studies were published between 1983 and 2006. Prostaglandin E2 was applied in a gel cervically and vaginally in some trials and as tablets or pessaries in other trials. Inclusion criteria varied across trials for inclusion of women with previous caesarean sections, preterm gestation prior to 37 weeks, parity, body mass index, presentation with gestational diabetes, hypertension, oligohydramnios and polyhydramnios and maximal Bishop score. Various catheter sizes, balloon volumes, prostaglandin types and preparations and dosing regimens were used. The extra-amniotic catheter balloon was applied with or without extra-amniotic saline solution infusion (EASI) and/or intravenous oxytocin. The maximum period of cervical ripening until labour was induced or the attempt was defined as failed ripening ranged from six hours to 48 hours. Definitions of the primary outcomes varied across the included studies.
Primary outcomes were proportion of patients with babies delivered by caesarean section and incidence of excessive uterine activity. Secondary outcomes were proportion of women who delivered vaginally within 24 hours of the beginning of ripening or within 12 hours from the beginning of the induction, proportion of patients with unfavourable or unchanged Bishop score 12 to 24 hours after ripening, interval from ripening to delivery time, need for oxytocin induction and/or augmentation of labour, adverse events and maternal and neonatal morbidity and mortality.
Two reviewers performed the study selection; any disagreements were resolved by consensus.