title: Daycare attendance, breastfeeding, and the development of type 1 diabetes: the diabetes autoimmunity study in the young.
abstract: BACKGROUND
  The hygiene hypothesis attributes the increased incidence of type 1 diabetes (T1D) to a decrease of immune system stimuli from infections. We evaluated this prospectively in the Diabetes Autoimmunity Study in the Young (DAISY) by examining daycare attendance during the first two years of life (as a proxy for infections) and the risk of T1D.
  
  
  METHODS
  DAISY is a prospective cohort of children at increased T1D risk. Analyses were limited to 1783 children with complete daycare and breastfeeding data from birth to 2 years of age; 58 children developed T1D. Daycare was defined as supervised time with at least one other child at least 3 times a week. Breastfeeding duration was evaluated as a modifier of the effect of daycare. Cox proportional hazards regression was used for analyses.
  
  
  RESULTS
  Attending daycare before the age of 2 years was not associated with T1D risk (HR: 0.89; CI: 0.54-1.47) after adjusting for HLA, first degree relative with T1D, ethnicity, and breastfeeding duration. Breastfeeding duration modified this association, where daycare attendance was associated with increased T1D risk in nonbreastfed children and a decreasing T1D risk with increasing breastfeeding duration (interaction P value=0.02).
  
  
  CONCLUSIONS
  These preliminary data suggest breastfeeding may modify the effect of daycare on T1D risk.
authors.affiliation: Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Katelyn
authors.identifier: 0000-0003-2588-3009
authors.initials: K
authors.lastname: Hall
authors.affiliation: Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Brittni
authors.identifier: 0000-0001-5547-202X
authors.initials: B
authors.lastname: Frederiksen
authors.affiliation: The Barbara Davis Center for Diabetes, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Marian
authors.identifier: 0000-0003-3829-9207
authors.initials: M
authors.lastname: Rewers
authors.affiliation: Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Jill M
authors.initials: JM
authors.lastname: Norris
mesh_terms: D001942:Breast Feeding / Q000706:statistics & numerical data*; D002656:Child Day Care Centers / Q000706:statistics & numerical data*; D002675:Child, Preschool; D003120:Colorado / Q000453:epidemiology; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012307:Risk Factors