title: Risk for postterm delivery after previous postterm delivery.
abstract: OBJECTIVE
  We examined the hypothesis that the risk for subsequent postterm birth is increased in women with an initial postterm birth.
  
  
  METHODS
  We performed a population-based cohort study of Missouri births (1989-1997) to assess the recurrence of postterm birth using the Missouri Department of Health's maternally linked database.
  
  
  RESULTS
  A total of 368,633 births were evaluated, of which 7.6% were postterm (>42 weeks of gestation). Black mothers had a lower risk for all (adjusted odds ratio [OR], 0.70; 95% CI, 0.67-0.73) or recurrent (adjusted OR, 0.73; 95% CI, 0.67-0.79) postterm birth. Maternal education of <12 years (adjusted OR, 1.51; 95% CI, 1.41-1.62), indices of low socioeconomic status, and maternal body mass index >35 kg/m2 (adjusted OR, 1.23; 95% CI, 1.11-1.37) were associated with increased risk for recurrent postterm birth. Mothers with an initial postterm birth were at increased risk for postterm birth (OR, 1.88; 95% CI, 1.79-1.97) in subsequent pregnancies, independent of race.
  
  
  CONCLUSIONS
  Among mothers who deliver postterm, there is a significant risk for subsequent postterm births. This increased risk suggests that common factors (genetic or other) influence the likelihood of abnormal parturition timing.
authors.affiliation: Washington University School of Medicine, Center for Preterm Birth Research, St Louis, MO 63110, USA.
authors.forename: Zachary A-F
authors.initials: ZA
authors.lastname: Kistka
authors.forename: Lisanne
authors.initials: L
authors.lastname: Palomar
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Boslaugh
authors.forename: Michael R
authors.initials: MR
authors.lastname: DeBaun
authors.forename: Emily A
authors.initials: EA
authors.lastname: DeFranco
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Muglia
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D011247:Pregnancy; D011273:Pregnancy, Prolonged / Q000453:epidemiology*; D012008:Recurrence; D012307:Risk Factors