Magnesium sulfate and risk of postpartum uterine atony and hemorrhage: A meta-analysis

Magnesium sulfate (MgSO₄) is among the most commonly used medications in labor and delivery units. It has been used as a mean to protect against eclampsia and a neuroprotective agent for fetuses at risk of preterm birth. In the present study we investigated its impact in the occurrence of postpartum uterine atony and hemorrhage.

We searched the Medline, Scopus, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL, Clinicaltrials.gov and Google Scholar databases for randomized trials and observational studies. Statistical analysis was performed with the Hartung-Knapp-Sidik-Jonkman model in RStudio using the meta package.

Twelve studies fitted the predetermined criteria and these involved 41,190 women of whom 10,565 (25.6 %) received MgSO_4. The meta-analysis revealed that the risk of postpartum uterine atony was similar among patients that received MgSO₄ and those that did not (OR 1.93, 95 % CI 0.78, 4.81). Estimated blood loss (SMD 0.04, 95 % CI -0.10, 0.18) as well as the risk of postpartum hemorrhage (OR 1.82, 95 % CI 0.99, 3.35) also did not differ. Subgroup analysis revealed that evidence drawn from observational studies indicates a significant effect of MgSO₄ on the odds of postpartum uterine atony and hemorrhage; however, randomized trials do not support this.

The results of our meta-analysis suggest that it is reasonable to consider MgSO4 in women at risk of delivering before the completion of its elimination half-life. However, physicians should be vigilant in cases at risk of postpartum hemorrhage as current data are very heterogeneous and should not be considered as definitive.