title: Latent protective effects of breastfeeding on late childhood overweight and obesity: a nationwide prospective study.
abstract: OBJECTIVE
  To investigate the latent effect of breastfeeding on overweight and obesity in late childhood.
  
  
  METHODS
  Data on breastfeeding and child anthropometric measurements were collected annually from a nation-wide population-based prospective cohort study in Japan (21,425 boys and 20,147 girls). Breastfeeding status (exclusiveness and duration) was assessed when the child was 6 months old. Mixed effects models were used to evaluate trajectories of body mass index (BMI), together with overweight and obesity status, from 1.5 to 8 years of age.
  
  
  RESULTS
  Mixed-fed boys and exclusively breastfed boys showed lower BMI as the main effect, as well as a slower increase of inclination in BMI as interaction term between feeding type and age, than exclusively formula-fed boys. Breastfed boys had lower BMI at the ages of 7 and 8, in comparison with exclusively formula fed boys (P = 0.002 and P < 0.001, respectively). A similar association was found for girls, although the main effect of feeding type was not statistically significant. The analysis of breastfeeding duration had similar results.
  
  
  CONCLUSIONS
  Breastfeeding, even if partial or for short duration, has a latent protective effect against overweight and obesity in late childhood, especially for boys.
authors.affiliation: Department of Social Medicine, National Research Institute for Child Health and Development, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Seung Chik
authors.initials: SC
authors.lastname: Jwa
authors.forename: Takeo
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Naoki
authors.initials: N
authors.lastname: Kondo
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D001942:Breast Feeding; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007564:Japan; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000517:prevention & control*; D050177:Overweight / Q000517:prevention & control*; D011446:Prospective Studies; D065840:Protective Factors; D012959:Socioeconomic Factors
keywords: bottle feeding; breastfeeding; epidemiology; obesity; overweight