Defining and Managing Normal and Abnormal Second Stage of Labor.

The American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin No. 49 on Dystocia and Augmentation of Labor defines a prolonged second stage as more than 2 hours without or 3 hours with epidural analgesia in nulliparous women, and 1 hour without, or 2 hours with epidural in multiparous women. This definition diagnoses 10% to 14% of nulliparous and 3% to 3.5% of multiparous women as having a prolonged second stage. Although current labor norms remained largely based on data established by Friedman in the 1950s, modern obstetric population and practice have evolved with time.