title: Association between breastfeeding and body mass index at age 6-7 years in an international survey.
abstract: BACKGROUND
  Breastfeeding is believed to reduce children's risk for obesity but data are conflicting. It is also uncertain if breastfeeding has different effects on obesity in high- and low-income countries.
  
  
  OBJECTIVE
  This study aimed to investigate the association between having been breastfed and body mass index (BMI) in 6- to 7-year-old children in a large international survey.
  
  
  METHODS
  Parents/guardians reported whether their child had been breastfed and their current height and weight. Some centres measured height and weight directly. Analyses adjusted for whether height and weight were reported or measured, child's age, sex, country gross national income and centre.
  
  
  RESULTS
  Data were available for 76,635 participants from 31 centres in 18 countries. Reported breastfeeding rates varied from 27 to 98%. After adjusting for potential confounders, the estimated BMI difference was 0.04 kg m(-2) lower among those who had been breastfed (P = 0.07). The risk for being overweight or obese was slightly lower among breastfed children (odds ratio = 0.95, P = 0.012). There was no evidence that the association between breastfeeding and BMI was different in lower income countries compared with higher income countries.
  
  
  CONCLUSIONS
  The findings suggest that breastfeeding has little impact on children's BMI. Increasing breastfeeding is unlikely to reduce the global epidemic of childhood obesity.
authors.affiliation: Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand.
authors.forename: R J
authors.initials: RJ
authors.lastname: Hancox
authors.affiliation: School of Population Health, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand.
authors.forename: A W
authors.initials: AW
authors.lastname: Stewart
authors.affiliation: Medical Research Institute of New Zealand, Wellington, New Zealand.|Capital and Coast District Health Board, Wellington, New Zealand.
authors.forename: I
authors.initials: I
authors.lastname: Braithwaite
authors.affiliation: Medical Research Institute of New Zealand, Wellington, New Zealand.|Capital and Coast District Health Board, Wellington, New Zealand.
authors.forename: R
authors.initials: R
authors.lastname: Beasley
authors.affiliation: Department of Medicine, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand.
authors.forename: R
authors.initials: R
authors.lastname: Murphy
authors.affiliation: Department of Paediatrics: Child and Youth Health, Faculty of Medical and Health Sciences, The University of Auckland, New Zealand.
authors.forename: E A
authors.initials: EA
authors.lastname: Mitchell
mesh_terms: D015992:Body Mass Index; D001942:Breast Feeding / Q000706:statistics & numerical data*; D002648:Child; D003431:Cross-Cultural Comparison; D003430:Cross-Sectional Studies; D019049:Developed Countries / Q000706:statistics & numerical data; D003906:Developing Countries / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D016017:Odds Ratio; D063766:Pediatric Obesity / Q000453:epidemiology / Q000517:prevention & control*; D012307:Risk Factors; D011795:Surveys and Questionnaires
keywords: Body mass index; breastfeeding; children; obesity