(203) Predicting Prolonged Pushers: Risk Factors for Prolonged Second Stage at the Time of Full Dilation

Objective: A prolonged second stage of labor is associated with increased maternal and neonatal morbidity. Identifying patients at the start of the second stage at high risk for a prolonged second stage may help inform targeted clinical management strategies.

Study Design: Retrospective cohort of 1000 nulliparous patients with an epidural who reached full dilation at a single academic hospital in 2022. Patient characteristics were collected and charts reviewed to identify intrapartum factors. Active labor was considered protracted if time from the first exam at >/=6 cm to full dilation was > the 95% per contemporary labor nomograms. Contractions were considered adequate if at least every 3 minutes, lasting 1 minute and moderate or strong. Station was considered high if < +1/5. Head position was determined by documentation at delivery accounting for earlier documentation of spontaneous/manual rotation. Statistical analysis performed in STATA; p< 0.05 used for statistical significance.

Results: The median length of the second stage was 1.5 hours (IQR 0.7-3.0).  132 patients (13.2%) had a prolonged second stage ( >4 hours), which was associated with higher rates of chorioamnionitis (28% vs. 11%), postpartum hemorrhage (16% vs. 5%), and NICU evaluation (39% vs. 18%) [p< 0.01 all]. Several factors were independently associated with prolonged second stage: birthweight > 4000g (aOR 2.2; 95%CI 1.2-4.1), protracted active labor (aOR 1.7 [1.2-2.6]), inadequate contractions (aOR 2.0 [1.3-3.0]), high station (aOR 2.4 [1.4-4.0]) and OP position (aOR 4.4 [2.8-7.0]). Using these factors, the risk of a prolonged second stage ranged from 5 to 83% in our cohort with 10% of patients at >30% risk.

Conclusion: Risk factors known at the start of the second stage (OP position, protracted labor, LGA, inadequate contractions, and high station) can identify patients at the highest risk for a prolonged second stage which may allow for targeted management strategies, such as active coaching, manual rotation, oxytocin titration, or an earlier threshold for operative delivery in high risk patients to reduce maternal/neonatal morbidity.