The Effect of Induction of Labor on Second Stage Duration in Nulliparous Women, before and after the ACOG and SMFM Change in Guidelines

Background: To examine the effect of induction of labor (IOL) on the length of second stage of labor in nulliparous, compared to spontaneous labor while considering the change in the Obstetricians and Gynecologists and the Society for Maternal Fetal Medicine (ACOG & SMFM) guidelines. Methods: A retrospective study of nulliparous women who delivered vaginally at a single center (2011- 2017). Second stage duration was compared between women with IOL to those who went into spontaneous labor, in the pre and post -guideline periods. Results: The study included 5222 nulliparous women. Women who had an IOL had more epidural analgesia and prolonged second stage of labor than those who went into spontaneous labor (95.2% vs. 71.9%, p < 0.0001 and 6.1% vs. 1%, p < 0.0001, respectively). Second-stage was longer in the IOL group, in pre-guidelines (mean duration 69 min vs. 151 min, p < 0.001), and in the post-guidelines period (mean duration 69 min vs. 146 min, p < 0.001), even after controlling for epidural analgesia. Conclusions: In one academic center the second-stage duration in nulliparous women who go through IOL, is longer than women who go into labor spontaneously in both the time frame before and after national changes in the definition of the second stage duration.