Effect of intravenous hyoscine-N-butyl bromide on active phase of labor progress: a randomized double blind placebo controlled trial

Introduction: Appropriate cervical dilatation and effacement are essential for the progression of labor. With the active management of labor, number of cesarean deliveries reduces and the duration of labor shortens. Cervical dilatation can be facilitated by mechanical, pharmacological and non-pharmacologic methods. Cervix is richly supplied by autonomic nerves, which may play a role in the dilatation of cervix. Hyoscine-N-butylbromide (HBB) is a muscarinic antagonist and acts as a cervical spasmolytic agent. After intravenous administration it is rapidly distributed into the tissues. We aimed to study the effects and safety of a single dose 20?mg HBB injection during the active phase of labor in both primi- and multigravid women.

Materials and method: A randomized, double-blinded, controlled trial, with healthy primigravid and multigravid women in spontaneous labor at term was considered in this study. Once the active phase of labor was achieved, either a single dose of 20?mg (1?mL) of HBB or placebo (1?mL saline) was given intravenously.

Results: The mean duration of the first stage of labor was 191.1?±?43.06?min in the primigravid patients of the HBB group, while it was 248.2?±?66.1?min in the placebo group, a statistically significant difference of 57?min (p?p?Conclusion: A single dose of 20?mg intravenous HBB is effective and safe in shortening the duration of the first stage of labor without any adverse effects on fetus and mother.