Cromi 2012.

Study characteristics
Methods	RCT
Participants	210 patients. Inclusion: singleton gestation, vertex presentation, BS ≤ 6, intact membranes, GA > 34 weeks, and reassuring fetal heart tracing on admission. Exclusion:antepartum bleeding, intrauterine fetal death, prior uterine scars, positive vaginal or rectal group B streptococcus screening cultures, placenta previa, other contraindication to vaginal delivery.
Interventions	Double‐balloon catheter (n = 105): inflated with 50 mL in either balloon. The double‐balloon device was left in place for approximately 12 hours. Dinoprostone vaginal insert 10‐mg controlled‐release (n = 105): in the vaginal fornix, max 24 hours
Outcomes	Vaginal delivery within 24 hours, improvement in the BS after ripening, caesarean delivery rates, ripening‐to‐delivery interval, oxytocin administration, epidural request, NICU admission, AS < 7 at 5 minutes, umbilical artery pH < 7.00.
Notes	Setting: University of In‐subria, Varese, Italy Study period: October 2010 to October 2011 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 randomisation scheme
Allocation concealment (selection bias)	Low risk	Concealment by keeping random allocation sequence in a file cabinet with access restricted to research staff?
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	High risk	Not an ITT analysis, women excluded after failed placement balloon or need for PGE2 gel after suppository expulsion.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes were reported in result
Other bias	Low risk	No other bias detected