Impact of new labor management guidelines on Cesarean rates among low-risk births at New York City hospitals: A controlled interrupted time series analysis.

PURPOSE: To examine the impact of the American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine (ACOG-SMFM) 2014 recommendations for preventing unnecessary primary Cesareans. METHODS: In a population-based cohort of births in New York City from 2012 to 2016, we used controlled interrupted time series analyses to estimate changes in age-standardized Cesarean rates among nulliparous, term, singleton vertex (NTSV) deliveries. RESULTS: Among 192,405 NTSV births across 40 hospitals, the age-standardized NTSV Cesarean rate decreased after the ACOG-SMFM recommendations from 25.8% to 24.0% (Risk ratio [RR]: 0.93; 95% CI 0.89, 0.97), with no change in the control series. Decreases were observed among non-Hispanic White women (RR: 0.89; 95% CI 0.82, 0.97), but not among non-Hispanic Black women (RR: 0.97; 95% CI 0.88, 1.07), Asian/Pacific Islanders (RR: 1.01; 95% CI 0.91, 1.12), or Hispanic women (RR: 0.94; 95% CI 0.86, 1.02). Similar patterns were observed at teaching hospitals, with no change at nonteaching hospitals. CONCLUSIONS: While low-risk Cesarean rates may be modifiable through changes in labor management, additional research, and interventions to address Cesarean disparities, are needed.