Labor Intervention and Outcomes in Women Who Are Nulliparous and Obese: Comparison of Nurse-Midwife to Obstetrician Intrapartum Care.

BACKGROUND

Women who are obese have slower labors than women of normal weight, and show reduced response to interventions designed to speed labor progress like oxytocin augmentation and artificial rupture of membranes. The optimal labor management for these women has not been described.

METHODS

This retrospective cohort study compared 2 propensity score-matched groups of women (N = 360) who were healthy, nulliparous, spontaneously laboring, and obese (body mass index ≥ 30 kg/m ). Labors were managed by either a certified nurse-midwife (CNM) or an obstetrician at one hospital from 2005 through 2012. Comparisons were made on a range of labor processes and outcomes.

RESULTS

Women who were obese and cared for in labor by CNMs were 87.0% less likely to have operative vaginal birth (adjusted odds ratio [aOR], 0.15; 95% confidence interval [CI], 0.06-0.41) and 76.3% less likely to have third- or fourth-degree perineal lacerations (aOR, 0.31; 95% CI, 0.13-0.79) compared to a matched group of women who were obese and had similarly sized neonates but who were cared for by obstetricians. The rates of unplanned cesarean birth, postpartum hemorrhage, maternal intrapartum fever, and neonatal intensive care unit admission were similar between groups. CNM patients were significantly less likely than patients of obstetricians to have labor anesthesia, synthetic oxytocin augmentation, or intrauterine pressure catheters. By contrast, CNM patients were significantly more likely than patients of obstetricians to use physiologic labor interventions, including intermittent fetal monitoring, ambulation, and hydrotherapy.

DISCUSSION

In women with spontaneous labor onset who were healthy, obese, and nulliparous, watchful waiting and use of physiologic labor interventions, characterizing CNM intrapartum care, were associated with outcomes that were similar to, or better than, those of women who were obese and exposed to more high-technology interventions characterizing intrapartum care by obstetricians. In women who were obese, physiologic labor interventions were safe for both mothers and neonates.