The investigators propose a large, multicenter, randomized clinical trial of immediate versus delayed pushing for nulliparous women in labor at term reaching complete cervical dilation. The central hypothesis is that immediate pushing in the second stage of labor increases spontaneous vaginal delivery, shortens duration of the second stage, and reduces adverse neonatal and maternal outcomes in nulliparous women. They will pursue the following specific aims: 1) Assess the effectiveness of immediate pushing at complete cervical dilation on the rate of spontaneous vaginal delivery in nulliparous women (Primary Aim), 2) Determine the effect of immediate pushing on the rate of neonatal composite morbidity (Secondary Aim #1), and 3) Determine the impact of immediate versus delayed pushing on objective and subjective measures of maternal pelvic floor morbidity (Secondary Aim #2). They estimate that randomizing a total of 3184 women will provide adequate statistical power to detect meaningful differences in the primary and secondary outcomes.