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CME Credit Offered
CME Credit Offered
Abstract Award
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Poster Session 3

(911) Maternal and Neonatal Morbidity after Prolonged Latent Labor

Friday, January 31, 2025
10:30 AM – 12:30 PM  
Objective: Cesarean delivery (CD) is often recommended after 12-18h of latent labor (LL) due to concern for futility/risk of morbidity. We sought to quantify the odds of morbidity and CD among individuals with prolonged LL.

Study Design: Secondary analysis of two MFMU labor studies: (1) APEX and (2) ARRIVE. We included those with singleton pregnancies ≥37w admitted for IOL who had LL ≥9h. We defined LL as <5cm dilated with rupture of membranes and exposure to oxytocin. Participants with LL 9-12h were compared to those with LL >12h (prolonged LL). The p</span>rimary outcome was maternal morbidity (ICU admission, sepsis, postpartum hemorrhage [PPH], unplanned procedure during hospitalization other than CD, thromboembolism); secondary outcomes were neonatal morbidity, PPH, intraamniotic infection (IAI), and CD. We used Liu cutpt methodology to evaluate the duration of LL that optimized sensitivity and specificity for morbidity.

Results: We included 2193 participants, 1000 of which had LL >12h. Of those with LL ≥12h, 12% had maternal and 16% had neonatal morbidity. Clinical characteristics are in Table 1. In the prolonged LL group, 61% delivered by CD.  Outcomes are shown in Fig 1a. Those with LL >12h had increased odds of maternal morbidity (aOR 2.4, 95% CI 1.7-3.2), neonatal morbidity (aOR 1.4, 95% CI 1.1-1.8), IAI (aOR 1.4, 95% CI 1.1-1.7), PPH (aOR 2.1, 95% CI 1.5-2.9), and CD (aOR 1.9, 95% CI 1.6-2.2). However, the duration of LL alone was a poor predictor of maternal morbidity (AUC 0.61 at 12h). Because the alternative to prolonged LL is CD, outcomes after >12h of LL were compared to a referent group of those having CD after 9-12h LL: there were increased odds of maternal morbidity and PPH among those who had a CS after >12h LL; there were not significantly increased odds of maternal morbidity, neonatal morbidity, PPH, or IAI among those who ultimately delivered vaginally. (Fig1b)

Conclusion: Prolonged LL was associated with increased overall morbidity, and CD may increase the risks associated with prolonged LL. The time point when morbidity associated with prolonged LL can be best mitigated with CD remains unknown.