title: Poor school performance is associated with a larger gain in body mass index during puberty.
abstract: OBJECTIVE
  Social inequalities in type 2 diabetes and coronary heart disease may be established in formative school years. We investigated whether school performance is associated with adiposity and increase in body mass index (BMI) between 10 and 15 years of age.
  
  
  METHODS
  A community sample of 2633 school children had height and weight measured in school at the ages of 10 and 15. Percentages of body fat and waist circumference were measured at the age of 15. Mean grades in several school subjects at the age of 15 (ninth school year) were divided into quartiles. A linear regression analysis with BMI as the main outcome took into account parental education and ethnicity, obtained from registers, and children's living habits, collected by questionnaires.
  
  
  RESULTS
  In adjusted models, longitudinal changes in BMI between the ages of 10 and 15 were larger in the lowest quartiles of school grades compared with the highest: for girls, they were β = 0.45 (p = 0.007) and for boys they were β = 0.45 (p = 0.016). Cross-sectional regression analyses, with percentage of body fat and waist circumference as outcomes, showed similar results.
  
  
  CONCLUSIONS
  Our results suggest that school performance is one pathway to social inequalities in obesity in school children.
authors.affiliation: Unit of Child and Adolescent Health, Centre for Epidemiology and Community Medicine, Health Care Services, Stockholm County Council, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Kark
authors.forename: A
authors.initials: A
authors.lastname: Hjern
authors.forename: F
authors.initials: F
authors.lastname: Rasmussen
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D015331:Cohort Studies; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D063766:Pediatric Obesity; D011627:Puberty / Q000502:physiology*; D013548:Sweden; D015430:Weight Gain
keywords: Body mass index; COMPASS study; Growth; School performance; Type 2 diabetes