Bower 1961.

Methods	Study described as a randomised controlled trial. Oldchurch Hospital, Essex, UK.
Participants	100 pregnant women who failed to obtain relief from antacid treatment for heartburn were recruited when attending outpatient antenatal care. Degree of heartburn of women was not stated at the study entry.
Interventions	Intervention group: intramuscular prostigmine 0.5 mg (N = 50) Comparison group: intramuscular water (N = 50)
Outcomes	Relief of heartburn (complete relief, useful relief), injection useless.
Notes	The authors stated that the average duration of relief obtained from the injections was 5 days. Otherwise, follow‐up is unclear.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Sequence generation not described.
Allocation concealment (selection bias)	Low risk	Pharmacy prepared identical ampoules with treatment and placebo, so that staff would not have been aware of the next group assignment when women were recruited.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Identical treatment and placebo.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Treatment allocation unknown to obstetric staff. Code broken after outcome data recorded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data for all women randomised.
Selective reporting (reporting bias)	Low risk	Planned outcomes appear to have been reported.
Other bias	Unclear risk	Duration of follow‐up not stated.