(557) The prognosis of unchanged cervical dilation in active labor during labor induction

In active labor, a cesarean delivery (CD) for arrest of dilation is indicated with unchanged cervical dilation over 4-6 hours. Outcomes after only 2 hours without cervical change in active labor are less well studied. We aimed to determine CD and maternal/neonatal morbidity rates associated with labor dystocia in the active phase among nulliparous patients in order to optimize counseling prior to reaching indication for CD.

Study Design:

We performed a retrospective cohort study of term, nulliparous, singleton gestations undergoing induction of labor (IOL) with unfavorable cervices and intact membranes who achieved active labor at a single institution in 2019. Patients with prior CD were excluded. Active labor dystocia was defined as the same cervical dilation over at least 2h after reaching 6cm. 3 groups were compared: (1) all who reached active labor, (2) active labor dystocia ≥ 2h, and (3) active labor dystocia ≥ 4h. Outcomes were CD rate and composite maternal/neonatal morbidity. Cochran-Armitage was used to evaluate for trends across dystocia duration.

Results:

Among 1309 inductions, 1095 (83.7%) reached active labor. 137 (12.5%) had the same active labor exam over two hours and 50 (4.6%) had the same exam over four hours. The overall rate of CD for patients that reached active labor was 15.4%. The CD rate was nearly 10x higher for patients with the same cervical dilation over 2h (52.6% vs. 15.4%, OR 9.8 95% CI[6.6-14.6]; Figure 1A), and even more elevated when cervical dilation remained unchanged in active labor for 4h (82.0% vs. 15.4%, OR 32.6 95%CI[15.5-68.7]; p-trend < 0.001). Maternal morbidity increased significantly by length of active labor dystocia (all who reached active labor: 21.7%; active labor dystocia ≥ 2h: 40.2%; ≥ 4h: 58.0%, p-trend < 0.001; Figure 1B). Neonatal morbidity was not impacted by active labor dystocia (p-trend=0.95; Figure 1C).

Conclusion:

CD and maternal morbidity rates are significantly higher in nulliparous patients experiencing active labor dystocia, even at the 2h mark. This point may be critical for patient counseling to prepare for the possibility of CD.