Clavin 1996.

Methods	RCT (number of sites not stated).
Participants	34 women. Inclusion criteria: not stated. Exclusion criteria: not stated. Setting: New Orleans, USA (timeframe not stated).
Interventions	MAGNESIUM VS NITROGLYCERIN 1) Magnesium sulphate IV ‐ no further details. 2) Nitroglycerin IV ‐ no further details.
Outcomes	Delivery delay 48 hrs, 1 week, and until 37 weeks; change of medication due to initial tocolysis drug failure or severe adverse effects; gestational age at birth; total days to birth.
Notes	Antenatal corticosteroid use: not stated. Surfactant use: not stated. Sample size calculation: stated. Funding: not stated. For failure of tocolysis because of continued contractions or severe adverse effects, women were switched to the other agent.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"prospectively randomized', no further details.
Allocation concealment (selection bias)	Unclear risk	No details provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No details provided but possible as both interventions were IV.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No details provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	7 of 15 women randomised to nitroglycerin were switched to magnesium. No details as to whether ITT analysis was conducted.
Selective reporting (reporting bias)	Unclear risk	Not all expected outcomes were reported.
Other bias	Unclear risk	Lack sufficient details in the abstract to be able to judge.