The effects of topical magnesium sulfate on progression of effacement, dilatation and duration of labor in nulliparous women

Effacement and dilatation are important factors affecting the progress and duration of labor. Impairment in their progression can disrupt the normal progress of labor and lead to maternal and neonatal complications. For many years, topical magnesium sulfate has been used experimentally for labor progression in Iran. Therefore, this study was performed with aim to determine the effects of topical magnesium sulfate on progression of effacement, dilatation and duration of labor in nulliparous women.

This double-blind randomized clinical trial was conducted on 72 nulliparous women with term pregnancy that had referred to Tehran Mahdieh hospital for delivery from March 2016 to September 2017. The participants were randomly divided into two groups of magnesium sulfate and placebo (n=36 in each group). In the magnesium sulfate group (intervention), 10 cc of magnesium sulfate 50%, and in the control group, 10 cc of distilled water was poured on the cervix in the beginning of the active phase, and the labor progress was assessed in two groups. Data were analyzed by SPSS software (version 17) and using independent t-test, Mann-Whitney, Chi-square and Fisher's exact tests. P<0.05 was considered statistically significant.

Mean duration of active phase of first stage of labor was 1.75±1.13 hours in magnesium sulfate group and 3.85±1.87 hours in placebo group, that was 2.10 hours longer than magnesium sulfate group (P=0.001). The drop-in hemoglobin levels was significantly lower in magnesium sulfate group than in the control group (P=0.022). The number of normal vaginal delivery was higher in magnesium sulfate group, but this difference was not statistically significant (P=0.429). There were no significant differences between two groups in terms of neonatal Apgar score, ruptures in birth canal and the mother’s postpartum conditions (p>0.05).

The use of topical magnesium sulfate on the cervix in the active phase improves effacement and dilatation and shortens the duration of labor. Since there are very few studies on this subject, performing further studies are recommended.