Lokkegaard 2015.

Study characteristics
Methods	RCT
Participants	Inclusion criteria: intact membranes, cephalic position, BS ≤ 6, indication of IOL. Exclusion criteria: ruptured membranes, spontaneous labour, placenta praevia, acute fetal distress, asthma, glaucoma, latex allergy, infections (acute herpes, GBS, condylomata), previous CS
Interventions	1. Double balloon catheter (n = 412); 80 mL, max 12 hours, thereafter either AROM or start of oxytocin. 2. PGE2 3 mg tablet (n = 413), 2 dose a day (4‐5 hourly), max 2 days
Outcomes	Failed inductions, time interval from induction to delivery, mode of delivery, neonatal outcome as assessed by the AS after 5 minutes and referral to a neonatal care unit, subgroups by parity and indication for induction. Post hoc analyses included the percentage of women who gave birth within 24 hours and the need for additional oxytocin stimulation
Notes	Setting: multicentre, Denmark Study period: September 2002 to December 2005 Funding: the randomisation procedure was funded by ‘ Snedkermester Sophus Jacobsen & Astrid Jacobsens fond and the Danish Toyota Foundation. Declarations of interest: none declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated and was stratified for parity and department.
Allocation concealment (selection bias)	Low risk	Central allocation by telephone
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	Unclear risk	Not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	ITT, missing data reported, but evenly distributed.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcome measures were reported
Other bias	Low risk	No other bias detected