title: Breastfeeding and risk of atopic dermatitis up to the age 42 months: a birth cohort study in Japan.
abstract: OBJECTIVE
  The purpose of this study was to investigate the association between breastfeeding and atopic dermatitis (AD) up to the age 42 months.
  
  
  METHODS
  Data from a nationally representative population-based birth cohort study in Japan were used (N = 38,757). Feeding pattern and breastfeeding duration were investigated via questionnaires when infants were aged 6 months. Physician-diagnosed AD during the previous 1 year was ascertained via questionnaires when the children were aged 18, 30, and 42 months. The associations between feeding patterns or breastfeeding duration and physician-diagnosed AD from the age 6 to 42 months, categorized by AD status (no history of AD, episodic AD, and persistent AD), were analyzed using ordered logistic regression adjusted for covariates.
  
  
  RESULTS
  Breastfeeding was positively associated with AD, with dose-response association (P for trend < .001). Exclusively breastfed infants were 1.26 times more likely to have AD (95% confidence interval, 1.12-1.41) than infants fed formula alone. Furthermore, children with a longer breastfeeding duration were also significantly more likely to have AD (P for trend < .001).
  
  
  CONCLUSIONS
  Breastfeeding is associated with an increased risk of AD up to the age 42 months. Further study is needed to elucidate the mechanism underlying the association between breastfeeding and AD.
authors.affiliation: Department of Social Medicine, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo, Japan; Division of Developmental Social Medicine, Department of Public Health and Occupational Medicine, Mie University Graduate School of Medicine, Tsu, Mie, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Ito
authors.affiliation: Department of Social Medicine, National Research Institute for Child Health and Development, Setagaya-ku, Tokyo, Japan; Division of Developmental Social Medicine, Department of Public Health and Occupational Medicine, Mie University Graduate School of Medicine, Tsu, Mie, Japan. Electronic address: fujiwara-tk@ncchd.go.jp.
authors.forename: Takeo
authors.initials: T
authors.lastname: Fujiwara
mesh_terms: D001942:Breast Feeding / Q000009:adverse effects*; D002675:Child, Preschool; D015331:Cohort Studies; D003876:Dermatitis, Atopic / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D007223:Infant; D041943:Infant Formula; D007564:Japan / Q000453:epidemiology; D008297:Male
keywords: Allergy; Atopic dermatitis; Breastfeeding; Cohort study; Infant formula