title: Placental abruption and subsequent risk of pre-eclampsia: a population-based case-control study.
abstract: BACKGROUND
  Pre-eclampsia and placental abruption may share a common pathophysiologic mechanism, namely, uteroplacental ischaemia. The aim of this study was to investigate the association between placental abruption and risk of pre-eclampsia in a subsequent pregnancy, and to determine whether the association differs by the gestational age at the time of abruption.
  
  
  METHODS
  A nested case-control study among multiparous women in the Medical Birth Register of Finland from 1996-2010 was conducted. Cases of pre-eclampsia (n = 6487) and frequency matched controls (n = 25,948) were linked to the Hospital Discharge Registry to ascertain data on prior abruption. Abruption was categorised as preterm (<37 weeks) or term (≥37 weeks) based on the gestational age at delivery. We fit logistic regression models to evaluate the associations between abruption and the odds of pre-eclampsia in the subsequent pregnancy before and after adjusting for potential confounders.
  
  
  RESULTS
  Preterm abruption was associated with over a twofold increase in risk of pre-eclampsia [odds ratio (OR) 2.2, 95% confidence interval (CI) 1.5, 3.3] in a subsequent pregnancy. In contrast, term abruption was not associated with pre-eclampsia (OR 1.1, 95% CI 0.7, 1.7). The association between preterm abruption and pre-eclampsia was further elevated among women with a history of pre-eclampsia. Associations with preterm abruption were also strengthened when the outcome was pre-eclampsia with early delivery (<34 weeks).
  
  
  CONCLUSIONS
  These findings suggest that placental abruption in a prior pregnancy is associated with a different risk profile of pre-eclampsia based on the gestational age of the abruption-affected pregnancy.
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA.
authors.forename: Samantha E
authors.initials: SE
authors.lastname: Parker
authors.forename: Martha M
authors.initials: MM
authors.lastname: Werler
authors.forename: Mika
authors.initials: M
authors.lastname: Gissler
authors.forename: Minna
authors.initials: M
authors.lastname: Tikkanen
authors.forename: Cande V
authors.initials: CV
authors.lastname: Ananth
mesh_terms: D000037:Abruptio Placentae / Q000453:epidemiology* / Q000209:etiology; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005387:Finland / Q000453:epidemiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016017:Odds Ratio; D011225:Pre-Eclampsia / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology* / Q000209:etiology; D012042:Registries; D012307:Risk Factors
keywords: early onset; ischemic placental disease; placental abruption; pre-eclampsia