(564) Prolonged second stage: What is the likelihood of a safe, vaginal delivery?

ACOG has recently revised a clinical practice guideline defining a prolonged second stage labor as >3 hours, citing increased risk for adverse maternal and neonatal outcomes and lower likelihood of vaginal delivery at longer second stage durations. We aimed to measure how second stage duration is associated with vaginal delivery rate and adverse maternal and neonatal outcomes.

Study Design:

This was a retrospective cohort study of nulliparous, term patients with a singleton, vertex fetus (NTSV) delivered at a tertiary care center hospital from 6/1/2023-12/31/2023. Patients who did not achieve the second stage of labor were excluded. Patients were stratified into three groups based on second stage duration: < 3 hours, >3 hours but < 4 hours, or > 4 hours. The association between second stage duration and all outcomes was tested using the Cochran-Armitage test of trend.

Results:

700 patients were included. There was a significant decrease in vaginal delivery rate with increasing duration of the second stage (P-trend < 0.01). In contrast, there was a significant increase in operative vaginal delivery rate with increasing second stage duration (P-trend < 0.01). The rate of neonatal 5-minute Apgar < 7 increased with increasing second stage duration (P-trend 0.04); however, no other significant trends were noted for other markers of maternal morbidity or neonatal ICU admission.

Conclusion:

Patients who reached the second stage of labor were significantly less likely to achieve a vaginal delivery as the second stage duration increased. However, the overall vaginal delivery rate remained high, with a significant proportion of operative vaginal deliveries among those with a prolonged second stage.