title: [Social, familial, and behavioral risk factors for obesity in adolescents].
abstract: OBJECTIVE
  To examine the impact of different social, familial, and behavioral factors on the risk of developing obesity in adolescents.
  
  
  METHODS
  We performed a case-control study nested in a population-based cohort that was followed from birth in 1982. Cases were adolescents with obesity, as defined by the World Health Organization. Controls came from a randomly chosen sample of members of the cohort, examined in 1997 and 1998. Information concerning risk factors was obtained from cohort records that were collected at different ages. Multivariate analysis was carried out using logistic regression.
  
  
  RESULTS
  Risk factors varied according to sex. Among boys, a family income at birth above one minimum wage was associated with a six-fold increase in obesity, and the presence of trait anxiety in adolescence with a four-fold increase. In both sexes, a one-unit increase in pre-pregnancy maternal body mass index was associated with a 10% increase in obesity. Smoking, fat consumption, time spent watching television or performing physical activity, and concurrent maternal weight were not associated with obesity.
  
  
  CONCLUSIONS
  Our results show that it is important to stratify data from obesity studies according to sex. In addition, early-life factors were more strongly associated with obesity than factors present during adolescence. However, the possibility of reporting bias cannot be ruled out, especially in terms of the information provided on diet and physical exercise. Whenever possible, the study of concurrent risk factors for obesity in adolescence should take into account the confounding effect of early-life factors.
authors.affiliation: Universidade Federal de Pelotas (UFPel), Departamento de Clínica Médica, Avenida Duque de Caxias 250, Departamento de Medicina Social, Caixa Postal 464, CEP 96001-970, Pelotas, RS, Brasil. monteiro.po@terra.com.br
authors.forename: Paulo
authors.initials: P
authors.lastname: Monteiro
authors.forename: Cesar
authors.initials: C
authors.lastname: Victora
authors.forename: Fernando
authors.initials: F
authors.lastname: Barros
mesh_terms: D000293:Adolescent; D001519:Behavior; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D016022:Case-Control Studies; D005191:Family Characteristics; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D012307:Risk Factors; D017678:Sex Distribution; D012959:Socioeconomic Factors