title: Longitudinal modelling of body mass index from birth to 14 years.
abstract: BACKGROUND
  To examine the tracking of BMI from birth to age 14 years.
  
  
  METHODS
  Linear mixed model (LMM) analysis was used to model the trajectories of BMI (n = 1,403). Adiposity rebound was investigated for a subset of individuals (n = 173).
  
  
  RESULTS
  Adolescents who were overweight or obese at 14 years followed a different BMI trajectory from birth compared to those of normal weight. There was a difference between weight status groups for the timing of adiposity rebound (p < 0.001) and BMI at nadir (p < 0.001). The LMM depicted a significant difference in rate of change of BMI over time for males and females (p < 0.001), with female BMI increasing at a faster rate, and for weight status groups (p < 0.005), with the obese cohort having the faster increase in BMI over time. BMI at birth was significantly lower for the normal weight cohort compared to the overweight (p = 0.029) and obese (p = 0.019) cohorts.
  
  
  CONCLUSIONS
  This study introduces a powerful analytic tool, LMM, to model BMI and shows that weight status at 14 years is the result of a distinct path in earlier years. Compared to their normal weight peers, overweight and obese adolescents experience an earlier adiposity rebound, with a higher BMI at rebound.
authors.affiliation: School of Health Sciences, The University of Notre Dame Australia, Fremantle, Australia. pchivers1@nd.edu.au
authors.forename: Paola
authors.initials: P
authors.lastname: Chivers
authors.forename: Beth
authors.initials: B
authors.lastname: Hands
authors.forename: Helen
authors.initials: H
authors.lastname: Parker
authors.forename: Lawrence
authors.initials: L
authors.lastname: Beilin
authors.forename: Garth
authors.initials: G
authors.lastname: Kendall
authors.forename: Max
authors.initials: M
authors.lastname: Bulsara
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D009765:Obesity / Q000453:epidemiology*