Intravaginal magnesium sulfate as an alternative to intravenous dexamethasone for labor acceleration: first direct...

Labor acceleration remains a major challenge in obstetric care. Although intravenous (IV) dexamethasone has been shown to be effective for labor acceleration, its systemic adverse effects limit its use. Intravaginal magnesium sulfate (MgSO4) may offer a potential alternative; however, comparative studies are needed. This study compared the safety and efficacy of these interventions for labor acceleration.

This Bayesian adaptive, three-arm randomized controlled trial enrolled 150 women in latent labor and assigned them to receive intravaginal MgSO4 (50%; 10 mL), IV dexamethasone (8 mg), or usual care. The primary outcomes were labor duration and change in Bishop score; secondary outcomes included Apgar scores.

Both active treatments significantly improved Bishop scores compared with control at 6 hours (3.06 vs. 3.05 points; P<0.001), with no significant difference between them. However, intravaginal MgSO4 reduced labor duration more effectively. It shortened the latent phase by 3.0 hours (95% credible intervals [CrI], 2.2 to 3.9) compared with dexamethasone (1.8 hours; 95% CrI, 1.2 to 2.4) and the active phase by 1.99 hours (95% CrI, 1.03 to 2.99) compared with 1.09 hours (95% CrI, 0.54 to 1.71), with a posterior probability of superiority exceeding 99.9%. All neonates had Apgar scores ≥8.

Intravaginal MgSO4 produced cervical effacement and dilation comparable to IV dexamethasone but achieved a significantly greater reduction in labor duration. Given similar neonatal safety outcomes, these findings suggest that intravaginal MgSO4 may be a preferable first-line agent for labor acceleration.