Magnesium sulfate versus nifedipine for tocolysis: meta-analysis of randomized controlled trials

Preterm labor, defined as contractions occurring every 5-10 minutes with cervical changes before the 37th week of estimated gestation, is a significant cause of perinatal mortality. This meta-analysis aims to evaluate the effectiveness and safety of magnesium sulfate compared to nifedipine in managing preterm labor. The systematic review protocol was registered with PROSPERO (CRD42023422419). Manuscripts published up to September 2024 were systematically searched in databases. Dichotomous data were pooled as odds ratios using a random-effects model with the Mantel-Haenszel method, while continuous data were analyzed as mean ± standard deviation values, mean differences, and standardized mean differences using inverse-variance fixed-effects analysis. Fifteen randomized clinical trials (RCTs) were included, enrolling a total of 2,186 pregnant women. Nifedipine showed a greater effect compared to a 4-gram IV dose of magnesium sulfate. However, the efficacy of these tocolytics in prolonging pregnancy by 48 hours did not significantly differ between nifedipine and a 6-gram IV dose of magnesium sulfate. Additionally, magnesium sulfate was associated with more adverse drug reactions. The moderate certainty of evidence found here requires confirmation in large, adequately powered RCTs.