title: Maternal and obstetric complications of pregnancy are associated with increasing gestational age at term.
abstract: OBJECTIVE
  We sought to estimate when rates of maternal pregnancy complications increase beyond 37 weeks of gestation.
  
  
  METHODS
  We designed a retrospective cohort study of all low-risk women delivered beyond 37 weeks' gestational age from 1995 to 1999 within a mature managed care organization. Rates of mode of delivery and maternal complications of labor and delivery were examined by gestational age with both bivariate and multivariable analyses.
  
  
  RESULTS
  We found that, among the 119,254 women who delivered at 37 completed weeks and beyond, the rates of operative vaginal delivery (OR 1.15, 95% CI 1.09, 1.22), 3rd- or 4th-degree perineal laceration (OR 1.15, 95% CI 1.06, 1.24), and chorioamnionitis (OR 1.32, 95% CI 1.21, 1.44) all increased at 40 weeks as compared to 39 weeks of gestation (P < .001), and rates of postpartum hemorrhage (OR 1.21, 95% CI (1.10, 1.32), endomyometritis (OR 1.46, 95% CI 1.14, 1.87), and primary cesarean delivery (1.28, 95% CI 1.20, 1.36) increased at 41 weeks of gestation (P < .001). The cesarean indications of nonreassuring fetal heart rate (OR 1.81, 95% CI 1.49, 2.19) and cephalo-pelvic disproportion (OR 1.64, 95% CI 1.40, 1.94) increased at 40 weeks of gestation (P < .001).
  
  
  CONCLUSIONS
  We found that the risk of maternal peripartum complications increase as pregnancy progresses beyond 40 weeks of gestation. Management of pregnancies that progress past their EDC should include counseling regarding the risks of increasing gestational age.
authors.affiliation: Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, School of Medicine, 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: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011256:Pregnancy Outcome; D011273:Pregnancy, Prolonged / Q000453:epidemiology*; D012189:Retrospective Studies; D047929:Term Birth