Longitudinal modelling of body mass index from birth to 14 years.
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.
Chivers
Paola
P
School of Health Sciences, The University of Notre Dame Australia, Fremantle, Australia. pchivers1@nd.edu.au
Hands
Beth
B
Parker
Helen
H
Beilin
Lawrence
L
Kendall
Garth
G
Bulsara
Max
M
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*