title: Breastfeeding and behavioral development: a nationwide longitudinal survey in Japan.
abstract: OBJECTIVE
  To prospectively examine the prolonged effect of breastfeeding on behavioral development.
  
  
  METHODS
  We used a large, nationwide Japanese population-based longitudinal survey that began in 2001. We restricted participants to term singletons with birth weight >2500 g (n = 41 188). Infant feeding practice was queried at age 6-7 months. Responses to survey questions about age-appropriate behaviors at age 2.5 and 5.5 years were used as indicators of behavioral development. We conducted logistic regression analyses, controlling for potential child and parental confounding factors, with formula feeding as the reference group.
  
  
  RESULTS
  We observed a dose-response relationship between breastfeeding status and an inability to perform age-appropriate behaviors at both ages. With a single exception, all ORs for outcomes for exclusive breastfeeding were smaller than those for partial feeding of various durations. The protective associations did not change after adjustment for an extensive list of confounders or in the sensitivity analyses.
  
  
  CONCLUSIONS
  We observed prolonged protective effects of breastfeeding on developmental behavior skills surveyed at age 2.5 and 5.5 years. Beneficial effects were most likely in children who were breastfed exclusively, but whether a biological ingredient in breast milk or extensive interactions through breastfeeding, or both, is beneficial is unclear.
authors: Department of Human Ecology, Okayama University Graduate School of Environmental and Life Science, Okayama, Japan. Electronic address: yorichan@md.okayama-u.ac.jp.
authors: Takashi
authors: T
authors: Yorifuji
authors: Department of Pediatrics, Okayama Medical Center, National Hospital Organization, Okayama, Japan.
authors: Toshihide
authors: T
authors: Kubo
authors: Department of Human Ecology, Okayama University Graduate School of Environmental and Life Science, Okayama, Japan.
authors: Michiyo
authors: M
authors: Yamakawa
authors: Department of Public Health and Public Policy, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
authors: Tsuguhiko
authors: T
authors: Kato
authors: Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Department of Child and Adolescent Psychiatry, Okayama Psychiatric Medical Center, Okayama, Japan.
authors: Sachiko
authors: S
authors: Inoue
authors: Department of Human Ecology, Okayama University Graduate School of Environmental and Life Science, Okayama, Japan; Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors: Akiko
authors: A
authors: Tokinobu
authors: Department of Epidemiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan.
authors: Hiroyuki
authors: H
authors: Doi
mesh_terms: D001942:Breast Feeding / Q000523:psychology* / Q000706:statistics & numerical data; D002652:Child Behavior; D002653:Child Behavior Disorders / Q000517:prevention & control*; D002657:Child Development; D002675:Child, Preschool; D002658:Developmental Disabilities / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007223:Infant; D007564:Japan; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D013997:Time Factors