(921) Impact of Papaverine on Labor Outcomes Among Primiparous Patients Undergoing Induction of Labor

Antispasmodics such as papaverine, a musculotropic smooth muscle relaxant, are widely used during labor to facilitate cervical dilatation and to potentially shorten labor duration, though their efficacy and safety are unclear. We aimed to evaluate the impact of papaverine administered during labor induction, on maternal and neonatal outcomes among primiparous women.


Study Design:

This retrospective cohort study included 1,889 primiparous women who underwent labor induction with intravenous oxytocin during 2020–2024. The patients were classified according to papaverine administration: none (n=1,185), one dose (n=618), and two doses (n=86). The primary outcome was the mode of delivery. Secondary maternal outcomes included delivery within 24 hours, postpartum hemorrhage, and puerperal endometritis. Neonatal outcomes included a 5-minute Apgar score < 7, umbilical cord pH < 7.1, and admission to the neonatal intensive care unit. Multivariate logistic regression analysis was conducted to identify predictors of cesarean delivery.

 


Results:

Among women who received one and two doses of papaverine, compared to those who received none, the rates were lower of cesarean delivery due to non-progressive labor (11.5% and 14.0%, vs. 17.1%, p=0.002) (Table). Vaginal delivery rates were higher among women who received papaverine before rupture of membranes (77.0%) than those who received it after rupture (73.0%) and those who did not receive papaverine (66.1%) (p< 0.001) (Figure). In multivariate analysis, papaverine administration was associated with a reduced likelihood of cesarean delivery (odds ratio 0.64, 95% confidence interval 0.50–0.81, p< 0.001). Neonatal outcomes, including Apgar scores and admission to the neonatal intensive care unit, were similar across the groups.


Conclusion:

Among primiparous patients, papaverine administration, particularly before rupture of membranes, was associated with lower cesarean delivery rates due to non-progressive labor and with shorter labor duration, yet similar adverse maternal and neonatal outcomes. Randomized controlled studies are needed to confirm these findings.