OBJECTIVE: To estimate whether passive descent in the second stage of labor in morbidly obese parturients is associated with reduced active pushing times and improved labor outcomes compared with immediate pushing. METHODS: This was a retrospective cohort study of all consecutive women with a body mass index (BMI) of 40 or greater admitted for term labor that reached the second stage of labor from 2004 to 2008 at a single institution. Detailed information was collected for maternal demographics, labor progress, and neonatal outcomes. Length of active pushing, length of total second stage, and maternal and neonatal outcomes were compared between women selected to passive descent for at least 30 minutes and those who pushed immediately. RESULTS: A total of 558 women with a BMI of 40 or greater were identified; of these, 97 underwent passive descent and 461 pushed immediately. Morbidly obese women selected for passive descent were just as likely to actively push for at least 60 minutes compared with those who pushed immediately (16.5% compared with 7.2%, adjusted odds ratio [OR] 1.51, 95% confidence interval [CI] 0.74-3.12). They were also significantly more likely to push for more than 30 minutes (37.1% compared with 13.9%, adjusted OR 2.03, 95% CI 1.17-3.54). Their overall time (minutes) spent pushing was significantly longer (median 19, interquartile range 7-39 compared with median 7, interquartile range 3-17, P<.001) as was their overall length of second stage (median 81, interquartile range 57-127 compared with median 15, interquartile range 8-27, P<.001). They had similar rates of operative delivery and maternal febrile morbidity. CONCLUSION: Passive descent of morbidly obese parturients was associated with a greater amount of time actively pushing with similar rates of operative delivery and maternal febrile morbidity.