Chau 1992.

Methods	2‐centre quasi‐RCT.
Participants	98 women. Inclusion criteria: a clinical diagnosis of preterm labour. Gestational age range: 23‐35 weeks' and estimated fetal weight between 500‐2500 g. Exclusion criteria: women with ruptured membranes, multiple gestation, various maternal diseases, fetal death, congenital abnormality, obstetric haemorrhage, advanced cervical dilatation (≥ 4 cm), maternal or fetal condition making delivery advisable. Setting: New Orleans, Louisiana, USA, 1989‐1991.
Interventions	MAGNESIUM VS BETAMIMETICS 1) magnesium sulphate (n = 46) ‐ loading dose 4g IV MgSO4 over 30 minutes. Maintenance at 2 g/hr. Continued for 24 hrs or until no contractions for 12 hrs. Maximum 4 g/hr; 2) terbutaline (n = 52) ‐ loading dose 0.25 mg subcutaneously every 30 minutes for 3 doses and then 4 hourly for 24 hrs, or until contractions were absent for at least 12 hrs. 30 minutes prior to completion of IV therapy women in the magnesium sulphate group commenced oral 2‐3 g magnesium gluconate, and women in the terbutaline group started 5 mg terbutaline every 4‐6 hrs.
Outcomes	Delay in birth for 48 hrs, 1 week or until 37 weeks; time from tocolytic initiation to birth, gestational age at birth; birthweight, Apgar scores, infectious complications, adverse effects.
Notes	Antenatal corticosteroid use: not stated. Surfactant use: not stated. Sample‐size calculation: stated. Funding: not stated. In case of failure of tocolysis because of continued contractions or inability to tolerate an effective dose, women were switched to the other agent.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"patients received either magnesium or terbutaline depending upon the last digit of their assigned hospital number."
Allocation concealment (selection bias)	High risk	Inadequate allocation as last digit of hospital number was used for randomisation.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Women and researchers unlikely to be blinded as intervention was subcutaneous or IV; there was no placebo.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No details provided, but unlikely.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No reporting of losses and ITT analysis was conducted.
Selective reporting (reporting bias)	Unclear risk	Not all expected neonatal outcomes were reported.
Other bias	Unclear risk	Some imbalance ‐ numbers differ between groups (46 in magnesium group and 52 in the no magnesium group).