Abstract Background: the second stage of labor is often the most stressful part of the childbearing process for the woman and fetus, and consequently for the provider. duration of the second stage of labor is influenced by many factors. Methods: prospective cohort study was conducted among mothers who gave birth in selected health facilities of Bahir Dar city from September to December 2017. Data were collected using face to face interviews, document review, and anthropometric measurement techniques. the data were entered into EPI DATA version 3.1 and exported to STATA version 12 for analysis. Both descriptive (frequencies, percentages and median time for second stage labor) and analytic statistics (Cox regression analysis) were performed. The proportional hazard assumption test was done using the Schonefeld residual. Result: The overall median duration of the second stage of labor was found to be 40.9 minutes.Lack of physical activity, the inadequacy of uterine contraction, occipito-posterior fetal position, and birth weight of greater than 4000 grams, and inadequacy of maternal pelvis were predictors of prolonged second stage of labor. Conclusion: Lack of Physical activity, the inadequacy of uterine contraction, occipito-posterior fetal position, and birth weight of greater than 4000 grams, and inadequacy of maternal pelvis were predictors of the prolonged second stage of labor. Keywords: second stage, childbirth, prolonged labor