Does hyoscine N-butylbromide shorten the active phase in labor? A meta-analysis of randomized controlled trials

Objectives: The objective of the study is to evaluate the therapeutic effect of hyoscine N-butylbromide (HBB) in active phase of labor and its safety to mother and fetus. Methods: A systematic literature search was conducted on Cochrane Library, Pubmed, EMBASE, CINAHL, ClinicalTrials.gov and three databases in Chinese up to March 31, 2020. Randomized controlled trials (RCTs) of HBB administration during the active phase for shortening of spontaneous labor at term compared with placebo were included. Two reviewers assessed the methodological quality and data extraction independently. We calculated pooled risk ratios (RRs), mean differences (MDs) and 95% confidence intervals (CIs) using Review Manager 5.3 software. Intention-to-treat principles and random-effects model were adopted for analysis and pool results. Results: In total, 1448 women from 9 RCTs were included in the meta-analysis. The HBB group exhibited significantly decreased durations of active phase (MD −61.1 min; 95% CI: −87.7 to −34.4, I²: 96%), the second stage (MD −2.0 min; 95% CI: −3.4 to −0.5, I²: 62%), and third stage (MD −0.7 min; 95% CI: −1.1 to −0.3, I²: 51%). Intravenous (IV) HBB group and intramuscularly (IM) HBB group were compared to the control group (MD −60.9 min; 95% CI −87.7 to −34.1, I²: 96%). No significant differences were observed in Cesarean section, post-partum hemorrhage, instrumental labor, Apgar scores or any adverse effects. Conclusion: Hyoscine N-butylbromide had a significant effect of shortening the duration of the active phase of labor without adverse effects. We recommend a single dose of intravenous administrated HBB when a woman undergoes labor augmentation.