Magnesium sulfate compared with nifedipine for acute tocolysis of preterm labor: a randomized controlled trial.

Objective: To compare the efficacy and side effects of intravenous magnesium to oral nifedipine for acute tocolysis of preterm labor.

Methods: A multicenter randomized trial was performed. Patients in active preterm labor who were at 24 to 33 weeks and 6 days of gestation were randomly assigned to receive magnesium sulfate or nifedipine.