title: Racial Differences in the Association between Parity and Incident Stroke: Results from the REasons for Geographic and Racial Differences in Stroke Study.
abstract: BACKGROUND
  Circulatory and vascular changes across consecutive pregnancies may increase the risk of later-life cerebrovascular health outcomes.
  
  
  METHODS
  The association between parity and incident stroke was assessed among 7674 white and 6280 black women, aged 45 years and older, and enrolled in the REasons for Geographic and Racial Differences in Stroke Study from 2003 to 2007. Parity was assessed at baseline, and incident stroke was ascertained from physician-adjudicated medical records through September 2014. Cox proportional hazards models were used to estimate hazard ratios (HR) for the association between parity and stroke, adjusting for baseline measures.
  
  
  RESULTS
  At baseline, 12.7% of white women and 16.2% of black women reported 1 live birth, while 8.2% and 19.0%, respectively, reported 5 or more live births. Mean follow-up time was 7.5 years (standard deviation = 2.8); there were 447 incident strokes. A significant interaction between race and parity was detected (P = .05). Among white women, those with 5 or more live births had a higher stroke risk than those with 1 live birth (HR = 1.57; 95% confidence interval [CI] .93-2.65). However, the association was eliminated after adjustment for baseline characteristics (HR = 1.00, 95% CI .59-1.71). For black women, those with 5 or more live births had the highest stroke risk compared with those with 1 live birth (HR = 1.91, 95% CI 1.25-2.93), but the association was attenuated and no longer statistically significant after adjustment for confounders (HR = 1.40, 95% CI .89-2.18).
  
  
  CONCLUSIONS
  In adjusted models, no statistically significantassociations were observed between parity and stroke risk in a diverse cohort of U.S. women. Further studies are needed to elucidate the role of lifestyle and psychosocial factors in the race-specific associations that were observed.
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, UNC, Chapel Hill, North Carolina; Department of Obstetrics & Gynecology, UNC School of Medicine, Chapel Hill, North Carolina. Electronic address: cvladutiu@unc.edu.
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Vladutiu
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, UNC, Chapel Hill, North Carolina.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Meyer
authors.affiliation: Department of Public Health Sciences, MUSC, Charleston, South Carolina.
authors.forename: Angela M
authors.initials: AM
authors.lastname: Malek
authors.affiliation: Department of Obstetrics & Gynecology, UNC School of Medicine, Chapel Hill, North Carolina; Department of Maternal and Child Health, Gillings School of Global Public Health, UNC, Chapel Hill, North Carolina.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Stuebe
authors.affiliation: Department of Biostatistics, UAB School of Public Health, Birmingham, Alabama.
authors.forename: Aleena
authors.initials: A
authors.lastname: Mosher
authors.affiliation: Department of Cardiology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
authors.forename: Shivani
authors.initials: S
authors.lastname: Aggarwal
authors.affiliation: Department of Neurology, University of Cincinnati, Cincinnati, Ohio.
authors.forename: Dawn
authors.initials: D
authors.lastname: Kleindorfer
authors.affiliation: Department of Epidemiology, UAB School of Public Health, Birmingham, Alabama.
authors.forename: Virginia J
authors.initials: VJ
authors.lastname: Howard
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010298:Parity; D016016:Proportional Hazards Models; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000208:ethnology*; D014481:United States; D044465:White People / Q000706:statistics & numerical data*
keywords: Women; cohort; parity; pregnancy; prospective; race; stroke