Pennell 2009.

Study characteristics
Methods	RCT: generation of sequence unclear, sealed opaque envelopes, patient chose from a selection of 12.
Participants	Inclusion: primipara, GA > 36 weeks, intact membranes, BS < 4.singleton fetus, cephalic presentation, intact membranes. Exclusion criteria were age < 16 years, previous uterine surgery, low‐lying placenta, any active or purulent infection of the lower vaginal tract, or an abnormal pre‐induction FHR tracing
Interventions	Foley catheter 30cc. (110). Atad catheter 80 cc. (107). PGE 2 gel 2 mg, 6‐hourly. (113).
Outcomes	Vaginal delivery within 24 hours, uterine hyperstimulation with/without FHR changes, CS, epidural analgesia, instrumental vaginal delivery, antibiotics during labour, postpartum haemorrhage, maternal fever during labour, pH < 7.10, placental abruption, endometritis, wound infection.
Notes	Data for Foley catheter and double balloon catheter were entered in 1 comparison (any mechanical method versus PG). Setting: King Edward Memorial Hospital (KEMH) in Perth, Western Australia Dates of study: July 2001 to December 2003 Funding sources: supported by a grant from the Women and Infants Research Foundation, King Edward Memorial Hospital, Perth, Australia. Adeza Biomedical Corporation contributed support for the fetal fibronectin test kits. Declarations of interest: none declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information about sequence generation process in the paper.
Allocation concealment (selection bias)	Low risk	Sealed opaque envelopes (but why selection of 12??).
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not feasible due to nature of intervention.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Research midwives were blinded to treatment allocation, especially important for satisfaction questionnaires.
Incomplete outcome data (attrition bias) All outcomes	Low risk	ITT, loss to follow‐up is described, incomplete data not mentioned.
Selective reporting (reporting bias)	Low risk	All outcomes prespecified in methods were reported, report includes all expected outcomes.
Other bias	Low risk	No other bias detected.