Attanayake 2014.

Methods	Double blind RCT.
Participants	Setting: Academic Obstetric Unit of the Teaching Hospital Mahamodara, Galle, Sri Lanka. Inclusion criteria: uncomplicated pregnancy at 39 weeks' gestational age (GA) with a singleton fetus having a cephalic presentation and a modified Bishop score < 5 out of 10, and consenting to self‐administer the vaginal tablets every other day for 5 days. Exclusion criteria: any pregnancy complications, e.g. hypertension or hyperglycaemia in pregnancy, multiple pregnancies, planned caesarean birth, fetal growth restriction and history of hypersensitivity or idiosyncratic reaction to nitrates.
Interventions	Intervention: self‐administer vaginally at home every other day, 5 doses of 60 mg of the sustained release form of isosorbide mononitrate (ISMN) from 273 days to 282 days. Control: pyroxidine 10 mg, using same regimen. In both arms, participants were instructed to self‐administer the tablets vaginally at home at GAs of 39 weeks, 39 weeks + 2 days, 39 weeks + 4 days, 39 weeks + 6 days and 40 weeks + 1 day, unless spontaneous onset of labour (SOL) was established and she needed admission to hospital. If SOL was not established by 40 weeks + 2 days, all participants were admitted to hospital, the MBS was re‐assessed and artificial separation of membranes was carried out if feasible, and if not feasible, a cervical massage were carried out. Thereafter the routine management guideline for cervical ripening and IOL of the unit were followed using artificial separation of membranes, prostaglandin (PGE₂ 3 mg tablets) vaginally or intra cervical Foley catheter, followed by amniotomy and intravenous oxytocin infusion, if SOL was not established by 41 weeks. On admission to hospital either with SOL or at 40 weeks + 2 days, compliance to the interventions was assessed by checking the cards which the participants had been requested to maintain, indicating when they self administered the study medication.
Outcomes	Outcomes stratified: Spontaneous onset of labour between 39 weeks and 40 weeks + 2 days Mode of birth between 39 weeks and 40 weeks + 2 days Modified Bishop score at GAs of 40 weeks + 2 days and 40 weeks + 5 days, and change in modified Bishop score between these dates Requirement of additional cervical ripening measures (vaginal PGE₂ or intracervical Foley catheter) between 40 + 5 weeks and 40 + 6 weeks Newborn outcomes: birthweight and vital status outcome; admission to SCBU Side effects (headache, dizziness, vomiting, nausea) Satisfaction and acceptability For pregnancies reaching 41 weeks: Modified Bishop score Requirement of IOL or augmentation Induction birth interval Mode of birth
Notes	This study was reported in a brief abstract. We attempted to contact authors for further information (1 September 2016), who provided an unpublished version of the manuscript (accepted for publication).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Article states "Using computer generated random numbers participants were allocated into the study and control groups by stratified (Primips / Multips) block randomization".
Allocation concealment (selection bias)	Low risk	Article states "Two sets of sequentially numbered opaque envelopes (one for Primips and one for Multips) were packed with five tablets of either ISMN–SR 60mgs (Angifree – SR, Microlabs, Bangalore, India) or five tablets of Pyridoxine 10mgs (HealthAid Vitamins, Harrow, Middlesex, United Kingdom ) according to the random allocation sequence in blocks of four, by the second author".
Blinding (performance bias and detection bias) Women	Unclear risk	Study title describes as double blind, no further detail provided.
Blinding (performance bias and detection bias) Clinical staff	Unclear risk	Study title describes as double blind, no further detail provided.
Blinding (performance bias and detection bias) Outcome assessor	Unclear risk	Study title describes as double blind, no further detail provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome data reported for all participants, except for 1 drop out from intervention arm (ISMN group) who discontinued due to anxiety.
Selective reporting (reporting bias)	Low risk	No evidence of selective reporting.
Other bias	Low risk	No other forms of bias identified.