Behrad 2003.

Methods	Randomised controlled trial.
Participants	Setting: Imam Reza’s Hospital, Iran. Participants: women (n = 100; 50 in the low‐dose group, 50 in the high‐dose group) between 24‐35 weeks' gestation with spontaneous preterm labour. Singleton and twin pregnancies were included. Definition of preterm labour: uterine contractions of more than 4 contractions per 20 minutes plus 1 of: cervical dilatation of at least 1 cm but less than 5 cm diameter, cervical effacement ≥ 80%, and/or progressive cervical dilatation and effacement. Exclusion criteria: higher‐order multiple gestations, rupture of membranes, non‐reassuring fetal assessment (abnormalities of the fetal heart rate pattern), evidence of intrauterine infection (temperature ≥ 38°C, leucocytosis, uterine tenderness, malodorous discharge), vaginal bleeding, patients with a history of diabetes mellitus, myasthenia gravis, any other neuromuscular diseases, impaired renal function (serum creatinine > 1.2 mg/dL), hypotension (mean arterial pressure < 70 mm Hg), maternal bradycardia (heart rate < 60 beats per minute), atrioventricular block, inability or refusal to provide informed consent.
Interventions	All women Bed rest in the labour unit. Corticosteroids: intramuscular dexamethasone 5 mg, 4 doses given 12 hours apart. Antibiotics: ampicillin 2 g every 6 hours for Group B Streptococcal prophylaxis if birth appeared imminent. Low‐dose group Loading dose: 4 g intravenous magnesium sulphate in a 20% solution over 20 minutes. Maintenance dose: 2 g/h magnesium sulphate by continuous infusion. High‐dose group Loading dose: 6 g intravenous magnesium sulphate. Maintenance dose: 2 g/h magnesium sulphate by continuous infusion. Increased by 1 g/h in the presence of continued contractions or cervical dilatation/effacement, hourly until successful tocolysis or failure of treatment.
Outcomes	Primary Median time to successful tocolysis (minutes). Serious neonatal morbidity and death. Secondary For the mother: self‐reported side effects; mode of birth. For the infant: birthweight, Apgar score less than 8 at 1 minute; Apgar score less than 8 at 5 minutes; respiratory distress; hypoglycaemia; bradycardia; hypocalcaemia. Health services outcomes: number of days in neonatal intensive care unit; length of stay. Total amount of time in the labour and delivery unit (minutes).
Notes	Mean age of women: 23.8 ± 5.2 years in the low‐dose group; 24 ± 4.4 years in the high‐dose group. Twin gestations: 3/50 in the low‐dose group; 1/50 in the high‐dose group. Approval for this study was granted from the institutional review board of the University of Mashhad Medical Sciences.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomly assigned by computer‐generated number allocation.
Allocation concealment (selection bias)	Low risk	Consecutively numbered opaque envelopes.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No details were given regarding blinding.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No details were given regarding blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up were reported.
Selective reporting (reporting bias)	Low risk	No obvious risk of selecting reporting.
Other bias	Low risk	No obvious risk of other bias.