Maternal and Neonatal Morbidity After 4 and 6 Hours of Protracted Active Labor in Nulliparous Term Pregnancies

To evaluate whether women with protracted active phase labor longer than 6 hours have an increased risk of adverse maternal and neonatal outcomes after the implementation of new labor management guidelines.

This was a retrospective study of nulliparous, term, singleton, vertex deliveries at Cedars Sinai Medical Center from August 2016 to September 2017. Women were included if they progressed to active phase labor, defined by cervical dilation of 6 cm or more. Women then were divided into three groups based on the time course of cervical change between 6 and 10 cm: 1) normal active phase: cervical change 1 cm or more within 4 hours throughout active labor; 2) mildly protracted active phase: cervical change 1 cm or less over 4-6 hours; and 3) very protracted active phase: cervical change 1 cm or less over 6 hours. Rate of change was assessed between cervical examinations. Primary outcome was a composite of maternal morbidity by study group. Secondary outcome was a composite of neonatal morbidity. We hypothesized that women with very protracted active phase had higher rates of adverse outcomes when compared with normal active phase. Regression analyses were performed to compare maternal and neonatal outcomes by study group.

There were 2,559 deliveries, of which 2,378 (90.8%) were vaginal deliveries. Composite maternal and neonatal morbidity was higher with longer labor. Maternal morbidity-very protracted active phase (42.0%) compared with normal active phase (22.6%) adjusted odds ratio (aOR) 2.15 (95% CI 1.62-2.86); mildly protracted active phase (39.5%) compared with normal active phase (22.6%) aOR 2.18 (95% CI 1.67-2.84). Neonatal morbidity: very protracted active phase (19.8%) compared with normal active phase (13.8%) aOR 1.38 (95% CI 0.98-1.96); mildly protracted active phase (19.4%) compared with normal active phase (13.8%) aOR 1.44; (95% CI 1.04-1.99). Composite maternal and neonatal morbidity was not different between mildly protracted and very protracted groups.

Composite maternal morbidity was greater in women with cervical change consistent with mildly protracted (4-6 hours) and very protracted (more than 6 hours) labor compared with cervical change in the normal active phase (less than 4 hours) group. However, composite maternal and neonatal morbidity was not different between mildly protracted and very protracted groups.