Wu 2017.

Methods	RCT
Participants	Inclusion: 18–40 years old; 37 + 0‐41 + 6 gestational weeks; BS ≤ 6; single alive fetus with cephalic presentation; in cephalopelvic proportion; without premature rupture of membrane; NST reaction type before labour induction. The indications of labour induction included delayed pregnancy, oligohydramnios (AFI = 3.0–8.0 cm), gestational diabetes mellitus, intrahepatic cholestasis of pregnancy, good control of gestational hypertension, with vaginal trial production condition and required pregnancy termination. Exclusion: placenta previa, vasa previa and APH; invasive cervical carcinoma; untreated HIV infection; allergic to induction drugs.
Interventions	Double‐balloon combined with IV drip of oxytocin (n = 60) AROM after 12 hours. IV drip of oxytocin at a concentration of 0.5% (n = 60); AROM after 12 hours If the patients did not enter the stage of active labour within 48 hours, the labour induction was regarded as failing, and other methods for pregnancy termination were used
Outcomes	Postpartum haemorrhage, cervical laceration, uterine rupture, puerperal infection, neonatal asphyxia, neonatal infection and meconium aspiration syndrome
Notes	Setting: China Study period: January 2014 ‐ June 2015 Funding: grants received from the Nature Science Foundation of China, the Science and Technology Project of Special Funds of Guangzhou, Guangdong Science and Technology Project, the Natural Science Foundation of Guangdong Province and Guangzhou Science and Technology Project Declarations of interest: none declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Women randomly divided, no information given
Allocation concealment (selection bias)	Unclear risk	No information reported on allocation concealment
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 not mentioned, but is reasonable as numbers are equal to randomised numbers. no missing cases or data
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes were reported
Other bias	Low risk	No other bias detected