Efficacy of hyoscine butyl-bromide in shortening the active phase of labor: Systematic review and meta-analysis of randomized trials

Introduction: Prolonged labor increases the risk of maternal and fetal complications. The active management of labor has been proven effective in lowering neonatal and maternal morbidity by shortening the duration of labor. Several pharmaceutical and non-pharmaceutical approaches are currently being used in the active management of labor. Hyoscine Butyl-bromide (HBB) is an antispasmodic and anticholinergic drug that acts as a cervical spasmolytic agent. It has been widely used in everyday practice for shortening the active phase of labor. Nonetheless, only a few trials have been conducted on the topic.

Objective: This review aimed to evaluate whether HBB is effective in decreasing the mean duration of the active phase of labor.

Study design: An electronic search was conducted on Medline (through PubMed), Scopus, ClinicalTrials.gov, EMBASE, PROSPERO, and Cochrane Library from the beginning of all databases to December 2019. Results were limited to randomized trials. Restriction for English language was applied. Inclusion criteria were: randomized clinical trials regarding primiparae or multiparae women with a singleton vertex pregnancy at term who were randomized to HBB versus placebo or other drugs. Primary outcome evaluated was the mean reduction of the active phase of labor.

Data collection and analysis: Eight randomized clinical trials, including 1159 pregnant women, were analyzed. Significant heterogeneity (I² = 99 %) between studies was noted for the primary outcome. The active phase of labor duration was significantly reduced in the treatment arm compared to controls [mean difference (MD) -83.93 min (95 % confidence interval (CI) -163.61, -4.25)]. Achieved reduction in primiparae women was -55.09 min [95 % CI -68.83, -41.35; I² = 37 %].

Conclusion: HBB is an effective treatment to shorten the duration of the active phase of labor in primiparae and multiparae women.