Objective: To examine associations between cervical dilation on admission and maternal and newborn outcomes in term spontaneous labor.
Methods: This is a retrospective cohort study of 11,368 singleton, term (37-43 6/7 weeks of gestation) spontaneously laboring women delivering in 14 hospitals in Washington State between 2012 and 2014 using chart abstracted data from the Obstetrics Clinical Outcomes Assessment Program. Women with prior cesarean delivery or ruptured membranes on admission were excluded. Pregnancy history, cervical dilation on admission, and outcomes were analyzed. Associations between early (less than 4 cm cervical dilation) and late (4 cm or greater cervical dilation) admission and outcomes were examined using general linear models with a log-link stratifying by parity. Results were reported as adjusted relative risks (RRs) with 95% confidence intervals (CIs).
Results: Early admission compared with late admission was associated with increased epidural use of 84.8% compared with 71.8% in nulliparous women and 66.3% compared with 53.1% in multiparous women (nulliparous RR 1.18, 95% CI 1.13-1.24; multiparous RR 1.25, 95% CI 1.18-1.32); oxytocin augmentation in 58.5% compared with 36.6% in nulliparous women and 45.9% compared with 20.7% in multiparous women (nulliparous RR 1.56, 95% CI 1.50-1.63; multiparous RR 2.14, 95% CI 1.87-2.44); and cesarean delivery of 21.8% compared with 14.5% in nulliparous women and 3.7% compared with 1.9% in multiparous women (nulliparous RR 1.50, 95% CI 1.32-1.70; multiparous women RR 1.95, 95% CI 1.47-2.57). Early admission was associated with increased neonatal intensive care unit admission for newborns of nulliparous women only (RR 1.38, 95% CI 1.01-1.89). Between 2012 and 2014, late admission increased 14.6% for nulliparous patients and 10.1% for multiparous patients, and the cesarean delivery rate decreased from 10.5% to 7.9% (P<.001) for all.
Conclusion: Early admission (less than 4 cm cervical dilation) is a risk factor for increased medical intervention and cesarean delivery.