[Tocolytic therapy with magnesium sulfate and terbutaline for inhibition of premature labor]

Magnesium sulfate has been recommended as a safe and effective tocolytic agent. However has not been substantiated by randomized, controlled trials. To assess the efficacy of magnesium sulfate, we initiated prospective randomized study competing the capabilities of magnesium sulfate and terbutaline for labor inhibition. The study population consisted of 30 patients (15 patients with terbutaline and 15 patients with magnesium sulfate) between 28 and 36 weeks of gestation and in preterm labor. One patient in terbutaline group was excluded of the study because we found a severe fetal distress. The diagnosis of labor was made if, persistent uterine contractions occurred at a frequency of at last three in a team-minute period and cervical examination suggested active labor. Success was defined as postponement of delivery for at least 48 hours after initiation of therapy. Despite a trend toward increased efficacy in the terbutaline group (tocolytic Bishop grade and its success) there were no significant differences between the two treatment groups with regard to capability of delaying delivery at least 48 hours. Although there were significant differences for terbutaline regard the tocolysis time. For all these reasons, the efficacy between both groups of treatment is similar, and in a future cases, will be necessary to choose the better agent for every case to study.