672: Complete without an urge to push: association of length of passive descent on labor outcomes

Abstract

To evaluate the association of the length of a passive second stage on complications of labor The pregnancy, labor, and delivery outcomes for Certified Nurse Midwife patients at a tertiary care hospital have been prospectively entered into a quality assurance database since 2006. These women were all considered appropriate for midwifery care prenatally and thus represent a relatively low-risk population. Term pregnancies without an indication for cesarean delivery on presentation to labor and delivery were eligible for analysis. It is the standard practice of the CNM group to encourage women with an epidural, no urge to push, and stable maternal and fetal status to have a passive second stage until the urge to push is felt. Recorded times for completed cervical dilation and the start of expulsive efforts were used to calculate passive descent time. Passive descent times greater than 2 standard deviations from the mean were excluded. Passive descent was treated as a continuous independent variable in three multiple logistic regressions predicting need for cesarean delivery (CD), development of clinical chorioamnionitis, and experience of a postpartum hemorrhage (>500mL for vaginal delivery and >1000mL for CD) respectively. The models were constructed using forward/backward model building techniques. Parity, maternal age, estimated gestational age, and neonatal weight were considered as additional independent predictors. We identified 2,279 low-risk labors cared for between 2008 and 2018, of whom 661 spent time in passive descent. 30 women were excluded from analysis for passive descent times greater than 248 min, two standard deviations above the mean time of 83 min (N=2,249 labors remained with passive descent times ranging from 0 to 225 min). Passive descent time was a significant predictor of maternal hemorrhage (P<0.01), chorioamnionitis (P=0.01), and CD (P<0.01; see Table 1). Increasing gestational age also predicted hemorrhage (P<0.01), whereas increasing maternal age predicted cesarean delivery. Nulliparity significantly predicted hemorrhage (P<0.01) and CD (P<0.01; see Table 1). In a low-risk population, prolonged time in passive second stage is associated with increased labor complications including a higher risk of CD. Efforts to reduce CD rates should consider limiting time spent in the passive second stage.