title: Association of Women's Reproductive History With Long-term Mortality and Effect of Socioeconomic Factors.
abstract: OBJECTIVE
  To assess the effects of socioeconomic factors on the association between parity and long-term maternal mortality.
  
  
  METHODS
  This was a population-based cohort study of mothers with births registered in the Medical Birth Registry of Norway during the period 1967-2009. We estimated age-specific (40-69 years) cardiovascular and noncardiovascular mortality ratios by number of births using Cox proportional hazard models. To assess effect modification by mothers' attained education, we stratified on low (less than 11 years) and high (11 years or greater) educational level. We further evaluated fathers' mortality by number of births using the same analytical approach.
  
  
  RESULTS
  Mothers with low education had higher mortality (cardiovascular: hazard ratio 2.62, 95% confidence interval [CI] 2.34-2.93, noncardiovascular: hazard ratio 1.67, 95% CI 1.62-1.73). Among mothers with low education, cardiovascular mortality increased linearly with each additional birth above one (P trend=.02). In contrast, among mothers with high education, cardiovascular mortality declined with added births (P trend=.045). For noncardiovascular mortality there was no association among mothers with low education, whereas mortality declined with increasing number of births among mothers with high education (P trend<.01). Father's mortality showed similar associations with number of births when stratified on maternal education.
  
  
  CONCLUSIONS
  Women's long-term mortality rose with number of births only for cardiovascular causes of death and only among mothers with low education. Partners of women with low education had similar increasing risk with increasing number of births. Maternal educational level is a strong modifier of the association between parity and long-term mortality.
  
  
  METHODS
  II.
authors.affiliation: Departments of Global Public Health and Primary Care and Clinical Sciences, University of Bergen, the Department of Obstetrics & Gynaecology, Haukeland University Hospital, the Medical Birth Registry of Norway, and the Norwegian Institute of Public Health, Bergen, Norway; and the Epidemiology Branch, National Institute of Environmental Health Sciences/National Institutes of Health, Durham, North Carolina.
authors.forename: Frode
authors.initials: F
authors.lastname: Halland
authors.forename: Nils-Halvdan
authors.initials: NH
authors.lastname: Morken
authors.forename: Lisa A
authors.initials: LA
authors.lastname: DeRoo
authors.forename: Kari
authors.initials: K
authors.lastname: Klungsøyr
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Wilcox
authors.forename: Rolv
authors.initials: R
authors.lastname: Skjærven
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000401:mortality; D002423:Cause of Death; D004522:Educational Status; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D010298:Parity; D016016:Proportional Hazards Models; D012042:Registries; D012923:Social Class