Yuen 1996.

Methods	RCT
Participants	Singleton vertex presentation, intact membranes, BS < 5, no previous CS.
Interventions	Atad device (100 mL) (36 women); intracervical PGE2 (0.5 mg) (39 women); vaginal pessary 0.5 mg PGE2 (39 women).
Outcomes	Change in BS, vaginal delivery achieved within 12 and 24 hours, CS, instrumental delivery, vaginal bleeding, uterine hyperstimulation, AS.
Notes	5 women were excluded (2, 2 and 1, respectively). Setting: Prince of Wales Hospital, Honkong teaching hospital, China Dates of study: period of 18 months Funding sources: not reported Declarations of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated number
Allocation concealment (selection bias)	Low risk	Sealed, 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	High risk	5 women excluded because of protocol violation, no other missing cases or data
Selective reporting (reporting bias)	Low risk	All pre‐specified outcome reported
Other bias	Low risk	No other bias detected