title: Change in paternity, risk of placental abruption and confounding by birth interval: a population-based prospective cohort study in Norway, 1967-2009.
abstract: OBJECTIVE
  We examined abruption risk in relation to change in paternity, and evaluated if birth interval confounds this association.
  
  
  METHODS
  Population-based study of singleton births in Norway between 1967 and 2009.
  
  
  METHODS
  Women who had their first two (n=747 566) singleton births in the Norwegian Medical Birth Registry. The associations between partner change between pregnancies and birth interval were examined in relation to abruption in a series of logistic regression models.
  
  
  METHODS
  Risk, as well as unadjusted and adjusted OR of placental abruption in relation to change in paternity and interval between births.
  
  
  RESULTS
  Among women without abruption in their first pregnancy, the risks of abruption in the second pregnancy were 4.7 and 6.5 per 1000 in women who had the same and different partners, respectively (OR=1.39, 95% CI 1.26 to 1.53). After adjustments for confounders including birth interval and smoking, partner change was not associated with abruption (OR=1.01, 95% CI 0.79 to 1.32). Among women with abruption in the first pregnancy, the association between partner change and abruption in the second pregnancy was 0.98 (95% CI 0.75 to 1.28). Interval <1 year was associated with increased abruption risk in the second pregnancy among women with the same as well as different partners, but interval over 4 years was only associated with increased risk among women with the same partner. No such patterns were seen for recurrent abruption.
  
  
  CONCLUSIONS
  We find no evidence that a change in partner is associated with increased abruption risk. Theories supporting an immune maladaptation hypothesis afforded by change in paternity are not supported insofar as abruption is concerned.
authors: Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, New York, New York, USA Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA.
authors: Cande V
authors: CV
authors: Ananth
authors: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway.
authors: Rolv
authors: R
authors: Skjaerven
authors: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway.
authors: Kari
authors: K
authors: Klunssoyr
mesh_terms: D000037:Abruptio Placentae / Q000209:etiology; D000293:Adolescent; D000328:Adult; D001721:Birth Intervals; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009664:Norway; D016017:Odds Ratio; D010298:Parity; D010334:Paternity; D011247:Pregnancy; D011446:Prospective Studies; D043762:Reproductive Behavior; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult
keywords: EPIDEMIOLOGY