title: Lactation Duration and Midlife Atherosclerosis.
abstract: OBJECTIVE
  To evaluate lactation duration in relation to subsequent atherosclerosis in women during midlife.
  
  
  METHODS
  The Coronary Artery Risk Development in Young Adults study is a multicenter prospective cohort that enrolled 2,787 women in 1985-1986 (ages 18-30 years, 52% black, 48% white), of whom 2,014 (72%) attended the 20-year follow-up examination in 2005-2006. We selected 846 women (46% black) without heart disease or diabetes at baseline who delivered one or more times after the baseline evaluation, had cardiometabolic risk factors measured at baseline, and had maximum common carotid intima-media thickness (mm) measured at the 20-year follow-up examination in 2005-2006. Lactation duration was summed across all postbaseline births for each woman and (n, women) categorized as: 0 to less than 1 month (n=262), 1 to less than 6 months (n=210), 6 to less than 10 months (n=169), and 10 months or greater (n=205). Multiple linear regression models estimated mean common carotid intima-media thickness (95% confidence interval) and mean differences among lactation duration groups compared with the 0 to less than 1-month group adjusted for prepregnancy obesity, cardiometabolic status, parity, and other risk factors.
  
  
  RESULTS
  Lactation duration had a graded inverse association with common carotid intima-media thickness; mean differences between 10 months or greater compared with 0 to less than 1 month ranged from -0.062 mm for unadjusted models (P trend <.001) to -0.029 mm for models fully adjusted for prepregnancy body mass index (BMI) and cardiometabolic risk factors, parity, smoking, and sociodemographics (P trend=.010). Stepwise addition of potential mediators (BMI, systolic blood pressure at the 20-year follow-up examination) modestly attenuated the lactation and common carotid intima-media thickness association to -0.027 and -0.023 mm (P trend=.019 and .054).
  
  
  CONCLUSIONS
  Shorter lactation duration is associated with subclinical atherosclerosis independent of prepregnancy cardiometabolic risk factors and traditional risk factors. The magnitude of differences in carotid artery intima-media thickness may represent greater vascular aging. Lactation may have long-term benefits that lower cardiovascular disease risk in women.
  
  
  METHODS
  II.
authors.affiliation: Division of Research, Kaiser Permanente Northern California, Oakland, and the Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California; the Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota; Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado; and the Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Erica P
authors.initials: EP
authors.lastname: Gunderson
authors.forename: Charles P
authors.initials: CP
authors.lastname: Quesenberry
authors.forename: Xian
authors.initials: X
authors.lastname: Ning
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Myron
authors.initials: M
authors.lastname: Gross
authors.forename: David C
authors.initials: DC
authors.lastname: Goff
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Pletcher
authors.forename: Cora E
authors.initials: CE
authors.lastname: Lewis
mesh_terms: D000328:Adult; D001942:Breast Feeding / Q000208:ethnology / Q000706:statistics & numerical data; D059168:Carotid Intima-Media Thickness; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D005006:Ethnicity; D005260:Female; D006801:Humans; D007774:Lactation / Q000208:ethnology / Q000378:metabolism; D016014:Linear Models; D008137:Longitudinal Studies; D015999:Multivariate Analysis; D011247:Pregnancy; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014481:United States / Q000453:epidemiology