Mathews 1967.

Methods	Performance bias: blinding of participants ‐ yes; blinding of caregiver ‐ yes; blinding of outcome assessment ‐ yes. Attrition bias: 15.6% of participants discontinued medication. Completeness of follow up: yes.
Participants	Country: UK. Number: 31 women in the intervention group, 33 women in the control group. Gestational age at trial entry: between 28 and 32 weeks.
Interventions	Isoxsuprine 30 mg 4 times a day versus placebo.
Outcomes	Incidence of: ‐ birth less than 36 weeks; ‐ neonatal mortality; ‐ birthweight less than 2500 grams. Mean gestational age. Mean birthweight.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear