History and Objectives: Due to importance of reducing the duration of the active phase of labor and controversies about effect of injection of Atropine-Promethazine combination on the duration of the active phase of labor, this study was performed on multiparous women referring to Shaheed Dr. Shabihkhani maternity hospital in Kashan in the second half of 1374 to evaluate the effects of injection of Atropine-Promethazine on the duration of active phase of labor.

Materials and Methods: A single-blinded clinical trial was performed on 2 experimental and control groups with intramuscular injection of 0.5mg Atropine and 25mg Promethazine and 2 milliliter distilled water respectively at the beginning of the active phase of labor. Onset of the active phase was characterized by 3 centimeters dilation and 50% effacement. The previous delivery was normal in all samples and rupture of amniotic sac occurred after the onset of the active phase of labor. Women with history of abortion, hypertension, diabetes cardiac disease twin pregnancy, abnormal fetal presentation and pelvic stricture were excluded from the study. Then duration of the active phase, i.e. the time from 3 centimeters to 10 centimeters dilation, was evaluated by repeated vaginal examinations and recorded.

Results: 200 multiparous women aged 18-35 years were studied. They were para 2 to para 4. Experimental and control groups each contained 100 patients that were age and para-matched. The duration of active phase of labor was 190±100 and 149±81 minutes in the experimental and control groups respectively. Injection of Atropine and Promethazine combination reduces the duration of the active phase of labor by 23.7% (P<0.001).

Conclusion: Considering the effect of Atropine-Promethazine combination in reducing the duration of the active phase of labor, its administration is recommended during labor.