Wang 2014.

Methods	RCT
Participants	Inclusion: oligohydramnios (AFI < 5 cm). GA beyond 37 0/7 weeks’, singleton pregnancy, vertex presentation, BS ≤ 6, intact membranes, the absence of documented uterine contractions, the absence of prior CS delivery, reassuring antenatal fetal testing (non‐stress test) active, and oxytocin challenge test negative upon study entry. Exclusion: antepartum bleeding, chorioamnionitis, placenta previa, or any other contraindication to vaginal delivery, women with documented PG allergy, maternal asthma history, vaginitis or cervicitis at presentation, and/or glaucoma history were not eligible for the pharmacological treatment arm
Interventions	Double balloon (n = 67): 80/80cc, no traction, max 12 hours. After 24 hours unsuccessful ripening start oxytocin 10 mg dinoprostone insert (n = 59), fornix posterior, max 24 hours, After 24 hours unsuccessful ripening start oxytocin
Outcomes	Pregnancy outcomes and success of induction
Notes	Setting: The People’s Liberation Army 174th Hospital, Xiamen, China, Study period: April 2010 ‐ February 2011 Funding: financial support of The People’s Liberation Army Nanjing Military Area Command Medicine Health Department in China. Declarations of interest: none declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described how random sequence was generated.
Allocation concealment (selection bias)	Low risk	Sealed envelope randomisation, opaque?
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	No ITT => 5 woman reassigned after randomisation (non re‐assuring FHR, failed placement) no missing data or cases
Selective reporting (reporting bias)	Unclear risk	No pre specified outcomes reported, so can't be judged
Other bias	Low risk	No other bias detected