title: Trends in childbirth before 39 weeks' gestation without medical indication.
abstract: BACKGROUND
  There is increasing attention to labor induction and cesarean delivery occurring at 37 0/7-38 6/7 weeks' gestation (early-term) without medical indication.
  
  
  OBJECTIVE
  To measure prevalence, change over time, patient characteristics, and infant outcomes associated with early-term nonindicated births.
  
  
  METHODS
  Retrospective analysis using linked hospital discharge and birth certificate data for the 7,296,363 uncomplicated births (>37 0/7 wk' gestation) between 1995 and 2009 in 3 states.
  
  
  METHODS
  Early-term nonindicated birth is calculated using diagnosis codes and birth certificate records. Secondary outcomes included infant prolonged length of stay and respiratory distress.
  
  
  RESULTS
  Across uncomplicated term births, the early-term nonindicated birth rate was 3.18%. After adjustment, the risk of nonindicated birth before 39 0/7 weeks was 86% higher in 2009 than in 1995 [hazard ratio (HR)=1.86; 95% confidence interval (CI), 1.81-1.90], peaking in 2006 (HR=2.03; P<0.001). Factors independently associated with higher odds included maternal age, higher education levels, private health insurance, and delivering at smaller-volume or nonteaching hospitals. Black women had higher risk of nonindicated cesarean birth (HR=1.29; 95% CI, 1.27-1.32), which was associated with greater odds of prolonged length of stay [adjusted odds ratio (AOR)=1.60; 95% CI, 1.57-1.64] and infant respiratory distress (AOR=2.44; 95% CI, 2.37-2.50) compared with births after 38 6/7 weeks. Early-term nonindicated induction was also associated with comparatively greater odds of prolonged length of stay (AOR=1.20; 95% CI, 1.17-1.23).
  
  
  CONCLUSIONS
  Nearly 4% of all uncomplicated births to term infants occurred before 39 0/7 weeks' gestation without medical indication. These births were associated with adverse infant outcomes.
authors.affiliation: *Division of Health Policy and Management, University of Minnesota School of Public Health, Minneapolis, MN †Children's Hospital of Philadelphia, Philadelphia, PA.
authors.forename: Katy B
authors.initials: KB
authors.lastname: Kozhimannil
authors.forename: Michelle
authors.initials: M
authors.lastname: Macheras
authors.forename: Scott A
authors.initials: SA
authors.lastname: Lorch
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000639:trends; D036861:Delivery, Obstetric / Q000639:trends*; D005260:Female; D005865:Gestational Age; D006801:Humans; D017063:Outcome Assessment, Health Care; D015995:Prevalence; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology