RESUMEN
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 < 0.001). The mean duration of the first stage of labor was 170.1 ± 50.8 min in the multigravid patients of the HBB group, while it was 224.06 ± 53.7 min in the placebo group (difference of 54 min, p < 0.001). The mean duration of the first stage of labor was significantly different both for multigravida and primigravid patients. There was no significant change in the times for the second and third stages of labor. There were no significant differences in terms of APGAR scores noted at 1 and 5 min, prepartum and postpartum hemoglobin levels and birth weight. No adverse maternal and fetal effects were observed in both HBB and placebo groups. 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.