Rameez 2007.

Methods	Double‐blind randomised controlled trial (stratified by parity) in an inpatient setting. Recruitment between August 2003 and April 2004 at the University Obstetric Unit, Teaching Hospital, Galle, Sri Lanka.
Participants	Women scheduled for admission for cervical ripening and labour induction. Inclusion criteria: included all of the following: uncomplicated singleton fetus, cephalic presentation, ≥ 41 completed weeks' gestation, modified Bishop score < 5. Exclusion criteria: any medical or obstetric problems or contraindications to ISMN.
Interventions	156 were randomised. 78 were prescribed 60 mg ISMN tablets and 78 received placebo (vitamin C) re‐examined after 48 hours. If cervix favourable (Bishop score ≥ 7) then they were induced the same day with amniotomy and oxytocin. if unfavourable then an intracervical extra amniotic Foley catheter was used to induce further ripening.
Outcomes	Maternal: caesarean section, additional induction agents used.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Block randomisation (stratified by parity).
Allocation concealment (selection bias)	Low risk	Sealed, opaque sequentially numbered envelopes.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No evidence to the contrary.
Selective reporting (reporting bias)	Low risk	No evidence to the contrary.
Other bias	Low risk	No evidence to the contrary.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Outcome assessor unaware of allocation. Suitable dummies used so patient blinded as well.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessor unaware of allocation. Suitable dummies used so patient blinded as well.