title: Who is at risk for prolonged and postterm pregnancy?
abstract: OBJECTIVE
  The objective of the study was to examine risk factors for postterm (gestational age >or= 42 weeks) or prolonged (gestational age >or= 41 weeks) pregnancy.
  
  
  METHODS
  We conducted a retrospective cohort study of all term, singleton pregnancies delivered at a mature, managed care organization. The primary outcome measures were the rates of pregnancies greater than 41 or 42 weeks' gestation. Multivariable logistic regression models were used to control for potential confounding and interaction.
  
  
  RESULTS
  Specific risk factors for pregnancy beyond 41 weeks of gestation include obesity (adjusted odds ratio [aOR], 1.26; 95% confidence interval [CI], 1.16-1.37), nulliparity (aOR, 1.46; 95% CI 1.42-1.51), and maternal age 30-39 years (aOR, 1.06; 95% CI, 1.02-1.10) and 40 years or older (aOR, 1.07; 95% CI, 1.02-1.12). Additionally, African American, Latina, and Asian race/ethnicity were all associated with a lower risk of reaching 41 or 42 weeks of gestation.
  
  
  CONCLUSIONS
  Our findings suggest that there may be biological differences that underlie the risk for women to progress to 41 or 42 weeks of gestation. In particular, obesity is a modifiable risk factor and could potentially be prevented with prepregnancy or interpregnancy interventions.
authors.affiliation: Department of Obstetrics and Gynecology, University of California, San Francisco, CA, USA.
authors.forename: Aaron B
authors.initials: AB
authors.lastname: Caughey
authors.forename: Naomi E
authors.initials: NE
authors.lastname: Stotland
authors.forename: A Eugene
authors.initials: AE
authors.lastname: Washington
authors.forename: Gabriel J
authors.initials: GJ
authors.lastname: Escobar
mesh_terms: D000328:Adult; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011273:Pregnancy, Prolonged / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult