Effect of intravaginal application of magnesium sulfate on the intensity of pain and duration of the first and second stages of labor in nulliparous women

Most pain relief methods are associated with some side effects and limitations. Magnesium sulfate, due to its osmotic properties and absorption of cervical water (moisture) can shorten labor duration and decrease labor pain via improving effacement and cervical edema. The aim of our study was to evaluate the effect of intravaginal magnesium sulfate on pain severity and duration of the first and second stages of labor.

In this double-blind randomized clinical trial study, 70 nulliparous women were allocated into two groups after the beginning of the active phase of labor. In group 1, 10 ccs of magnesium sulfate 50% was poured on the whole cervix during the vaginal examination. In group 2, a placebo (sterile water) in a similar way and amount was used. Then the two groups were compared in variables of demographic, obstetrics, clinical, pain severity, duration of the first and second stages of labor, and maternal and neonatal outcomes.

In different dilatations, pain severity in group 1 was significantly lower (P=0.0001). The duration of the first and second stages of labor was shorter in group 1 (P =0.0001). The two groups were similar in neonatal outcomes, drug side effects, and treatment satisfaction (P >0.05).

Intravaginal magnesium sulfate improves the condition of the cervix, reduces the duration and the severity of labor pain, and has no medical or neonatal side effects.