Study	Reason for exclusion
Martin 1990	Randomised controlled trial. Setting: University of Mississippi Medical Center, Mississippi, USA. Participants: women (n = 44; 23 magnesium gluconate, 21 magnesium chloride) with preterm labour. Definition of preterm labour: not stated. Intervention: oral magnesium gluconate compared with oral magnesium chloride given for maintenance tocolysis after the successful arrest of labour with parenteral magnesium sulphate. Reason for exclusion This study did not examine different treatment regimens of parenteral magnesium sulphate as single agent tocolytic therapy for the arrest of preterm labour. Rather, it examined the use of different oral magnesium preparations for maintenance tocolysis given after the successful arrest of labour with parenteral magnesium sulphate.
Martin 1998	Randomised controlled trial. Setting: University of Mississippi Medical Center, Mississippi, USA. Participants: women (n = 47; 25 magnesium gluconate, 22 magnesium chloride) with preterm labour. Definition of preterm labour: presence of regular uterine contractions with a change in cervical exam. Intervention: oral magnesium gluconate compared with oral magnesium chloride given for maintenance tocolysis after the successful arrest of labour with parenteral magnesium sulphate. Reason for exclusion This study did not examine different treatment regimens of parenteral magnesium sulphate as single agent tocolytic therapy for the arrest of preterm labour. Rather, it examined the use of different oral magnesium preparations for maintenance tocolysis given after the successful arrest of labour with parenteral magnesium sulphate.
Zygmunt 2003	Open‐label, randomised, parallel‐group, actively controlled study. Setting: three study centres in Germany (Hessian, Giessen, Heidelberg). Participants: women (n = 46; 23 in treatment group) with preterm labour with indication for single agent tocolysis therapy with magnesium sulphate. Definition of preterm labour: not stated. Intervention: loading dose of 4 g magnesium sulphate administered over 30 minutes. Maintenance dose of 1‐2 g/h magnesium sulphate up to 21 days via (1) ready to use infusion solution with 24 g magnesium sulphate per 500 mL OR (2) infusion solution concentrate, diluted in carrier solution before administration 20 g/500 mL. Reason for exclusion This study did not examine different treatment regimens of parenteral magnesium sulphate as single agent tocolytic therapy for the arrest of preterm labour. All women were given the same treatment regimen using two different preparations of magnesium sulphate (ready to use infusion solution versus infusion solution concentrate diluted in carrier solution).

g: gram(s)
 g/h: gram(s) per hour
 mL: millilitre(s)