Suffecool 2014.

Methods	RCT
Participants	Inclusion criteria: nulliparous, 18 years or older, GA 37 weeks or more, singleton, cephalic presentation, intact membranes, BS < 6, admission for IOL. Exclusion criteria: contraindication for vaginal delivery (placenta praevia, non vertex presentation), ruptured membranes, severe pre‐eclampsia, suspected fetal growth restriction with abnormal dopplers, presence of a uterine scar, non reassuring FHR trace requiring medical intervention.
Interventions	1. 10 mg dinoprostone vaginal insert (n = 31), max 12 hours, if after 12 hours unfavourable cervix start with oxytocin 2. Double balloon (Cook) (n = 31), 80 mL, oxytocin started 6 hours after placement. Balloon removed after max 12 hours.
Outcomes	Time from insertion of ripening method until delivery, delivery rate < 24 hours, CS rate, time to active labour, rate of operative vaginal delivery, maternal or fetal adverse events
Notes	Setting: USA Study period: February 2011 ‐ September 2012 Funding: not reported Declarations of interest: none declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated numbers
Allocation concealment (selection bias)	Low risk	The allocation assignment was sealed in sequentially‐numbered, opaque envelopes
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, no missing data or cases.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes were reported in results
Other bias	Low risk	No other bias detected