title: The impact of hospital obstetric volume on maternal outcomes in term, non-low-birthweight pregnancies.
abstract: OBJECTIVE
  The impact of hospital obstetric volume specifically on maternal outcomes remains under studied. We examined the impact of hospital obstetric volume on maternal outcomes in low-risk women who delivered non-low-birthweight infants at term.
  
  
  METHODS
  We conducted a retrospective cohort study of term singleton, non-low-birthweight live births from 2007-2008 in California. Deliveries were categorized by hospital obstetric volume categories and separately for nonrural hospitals (category 1: 50-1199 deliveries per year; category 2: 1200-2399; category 3: 2400-3599, and category 4: ≥3600) and rural hospitals (category R1: 50-599 births per year; category R2: 600-1699; category R3: ≥1700). Maternal outcomes were compared with the use of the chi-square test and multivariable logistic regression.
  
  
  RESULTS
  There were 736,643 births in 267 hospitals that met study criteria. After adjustment for confounders, there were higher rates of postpartum hemorrhage in the lowest-volume rural hospitals (category R1 adjusted odds ratio, 3.06; 95% confidence interval, 1.51-6.23). Rates of chorioamnionitis, endometritis, severe perineal lacerations, and wound infection did not differ between volume categories. Longer lengths of stay were observed after maternal complications (eg, chorioamnionitis) in the lowest-volume hospitals (16.9% prolonged length of stay in category 1 hospitals vs 10.5% in category 4 hospitals; adjusted odds ratio, 1.91; 95% confidence interval, 1.01-3.61).
  
  
  CONCLUSIONS
  After confounder adjustment, few maternal outcomes differed by hospital obstetric volume. However, elevated odds of postpartum hemorrhage in low-volume rural hospitals raises the possibility that maternal outcomes may differ by hospital volume and geography. Further research is needed on maternal outcomes in hospitals of different obstetric volumes.
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR. Electronic address: snowden@ohsu.edu.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Snowden
authors.affiliation: Department of Obstetrics, Gynecology, California Pacific Medical Center, San Francisco, CA.
authors.forename: Yvonne W
authors.initials: YW
authors.lastname: Cheng
authors.affiliation: School of Nursing, Oregon Health & Science University, Portland, OR.
authors.forename: Cathy L
authors.initials: CL
authors.lastname: Emeis
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR.
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Caughey
mesh_terms: D000328:Adult; D001724:Birth Weight; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D061847:Hospitals, High-Volume; D061846:Hospitals, Low-Volume; D006780:Hospitals, Rural; D006786:Hospitals, Urban; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D015999:Multivariate Analysis; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000209:etiology*; D011247:Pregnancy; D011785:Quality Assurance, Health Care; D012189:Retrospective Studies; D012307:Risk Factors; D047929:Term Birth
keywords: maternal complication; obstetric volume; obstetrics; quality