782: Length of active labor and risk of adverse maternal and neonatal outcomes

Abstract

In 2012, contemporary labor curves from the Consortium on Safe Labor (CSL) were created utilizing mathematical modeling and entered clinical practice as NICHD guidelines, replacing older Friedman labor curves. However, the association between length of labor and adverse maternal or neonatal outcomes was not evaluated. We sought to assess the relationship between length of active labor in women undergoing vaginal delivery and the risk of adverse maternal or neonatal outcomes as defined by contemporary labor curves. We performed a secondary analysis of the CSL data, including information from electronic medical records from 19 hospitals across the U.S. from 2002 to 2008. Our inclusion criteria were women with a normal, singleton, term, vertex pregnancy experiencing a vaginal delivery, and having documentation of a cervical exam of 5 or 6cm. Duration of active labor was defined as the time from a cervical exam of 6 cm to 10cm. Forward interpolation was performed to estimate time of the 6cm cervical exam for women with only a 5cm exam documented. Composite adverse maternal and neonatal outcomes were created. Time in active labor was categorized into 5 groups (0-2, >2-4, >4-6, >6-8, >9 hours). Comparisons were made among the groups using multivariable logistic regression, controlling for maternal age, race, parity and body mass index. The CSL data includes 228,438 deliveries. Based on our inclusion criteria, 29,087 were included in our analysis. There is a 1.57 fold higher odds of an adverse neonatal outcome with labor lasting >9 hours compared to the 0-2 hours group (p-value <0.001, 95% CI 1.2-1.9). All groups demonstrated significantly increased odds for adverse maternal outcome compared to 0-2 hours. Any active labor length >4 hours has increased odds of either an adverse maternal or neonatal outcome compared to 0-2 hours. Recent NICHD guidelines regarding labor management utilizing contemporary labor curves have not analyzed risk of adverse perinatal outcomes to date. Therefore, our data uniquely demonstrates that a longer duration of contemporary active labor is associated with adverse maternal and neonatal outcomes. While longer duration of active labor is allowed in current NICHD guidelines with the goal to reduce cesarean delivery, our data suggests that further studies are needed to evaluate safe and effective management of active labor to optimize maternal and neonatal health.