title: Cesarean Outcomes in US Birth Centers and Collaborating Hospitals: A Cohort Comparison.
abstract: BACKGROUND
  High rates of cesarean birth are a significant health care quality issue, and birth centers have shown potential to reduce rates of cesarean birth. Measuring this potential is complicated by lack of randomized trials and limited observational comparisons. Cesarean rates vary by provider type, setting, and clinical and nonclinical characteristics of women, but our understanding of these dynamics is incomplete.
  
  
  METHODS
  We sought to isolate labor setting from other risk factors in order to assess the effect of birth centers on the odds of cesarean birth. We generated low-risk cohorts admitted in labor to hospitals (n = 2527) and birth centers (n = 8776) using secondary data obtained from the American Association of Birth Centers (AABC). All women received prenatal care in the birth center and midwifery care in labor, but some chose hospital admission for labor. Analysis was intent to treat according to site of admission in spontaneous labor. We used propensity score adjustment and multivariable logistic regression to control for cohort differences and measured effect sizes associated with setting.
  
  
  RESULTS
  There was a 37% (adjusted odds ratio [OR], 0.63; 95% confidence interval [CI], 0.50-0.79) to 38% (adjusted OR, 0.62; 95% CI, 0.49-0.79) decreased odds of cesarean in the birth center cohort and a remarkably low overall cesarean rate of less than 5% in both cohorts.
  
  
  CONCLUSIONS
  These findings suggest that low rates of cesarean in birth centers are not attributable to labor setting alone. The entire birth center care model, including prenatal preparation and relationship-based midwifery care, should be studied, promoted, and implemented by policy makers interested in achieving appropriate cesarean rates in the United States.
authors.forename: Patrick
authors.initials: P
authors.lastname: Thornton
authors.forename: Barbara L
authors.initials: BL
authors.lastname: McFarlin
authors.forename: Chang
authors.initials: C
authors.lastname: Park
authors.forename: Kristin
authors.initials: K
authors.lastname: Rankin
authors.forename: Mavis
authors.initials: M
authors.lastname: Schorn
authors.forename: Lorna
authors.initials: L
authors.lastname: Finnegan
authors.forename: Susan
authors.initials: S
authors.lastname: Stapleton
mesh_terms: D000328:Adult; D016550:Birthing Centers; D002585:Cesarean Section; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006761:Hospitals; D006801:Humans; D016015:Logistic Models; D008427:Maternal Health Services; D008880:Midwifery; D016017:Odds Ratio; D011247:Pregnancy; D012307:Risk Factors; D014481:United States; D055815:Young Adult
keywords: birth centers; cesarean birth; intrapartum care; perinatal safety; propensity score