title: Abnormal placentation: twenty-year analysis.
abstract: OBJECTIVE
  This study was undertaken to determine whether the rate of abnormal placentation is increasing in conjunction with the cesarean rate and to evaluate incidence, risk factors, and outcomes.
  
  
  METHODS
  Cases from 1982-2002 were identified by histopathologic or strong clinical criteria. Risk factors were assessed in a matched case-control study, and analyzed using conditional logistic regression models.
  
  
  RESULTS
  There were 64,359 deliveries, with cesarean rates increasing from 12.5% (1982) to 23.5% (2002). The overall incidence of placenta accreta was 1 in 533. Significant risk factors for placenta accreta in our final analysis included advancing maternal age (odds ratio [OR] 1.13, 95% CI 1.089-1.194, P < .0001), 2 or more cesarean deliveries (OR 8.6, 95% CI 3.536-21.078, P < .0001), and previa (OR 51.4, 95% CI: 10.646-248.390, P < .0001).
  
  
  CONCLUSIONS
  The rate of placenta accreta increased in conjunction with cesarean deliveries; the most important risk factors were previous cesarean delivery, previa, and advanced maternal age.
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of Chicago, Ill, USA.
authors.forename: Serena
authors.initials: S
authors.lastname: Wu
authors.forename: Masha
authors.initials: M
authors.lastname: Kocherginsky
authors.forename: Judith U
authors.initials: JU
authors.lastname: Hibbard
mesh_terms: D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects / Q000706:statistics & numerical data; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008423:Maternal Age; D016017:Odds Ratio; D010921:Placenta Accreta / Q000453:epidemiology* / Q000209:etiology* / Q000503:physiopathology; D010923:Placenta Previa / Q000150:complications; D010929:Placentation; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors