Birth Weight and Weight Changes from Infancy to Early Childhood as Predictors of Body Mass Index in Adolescence.

ABSTRACT

OBJECTIVE: To assess the time point during infancy and early childhood at which greater than expected weight gain is associated with overweight in adolescence. STUDY DESIGN: Current height, weight, and body mass index (BMI) were assessed in 1520 adolescents (mean age of boys, 15.52 ± 0.84 years; mean age of girls, 15.37 ± 0.77 years). Information on weight and height trajectories during infancy and early childhood (birth and 6 other time points) was extracted from mother-child booklets. Conditional relative weights were computed to estimate greater or lower than expected weight gain (ie, soft tissue gain at a specific age independent of linear growth), and their association with BMI in adolescence was investigated using linear regression analysis. RESULTS: The mean BMI in adolescence was 21.77 ± 3.69 in boys and 21.70 ± 3.50 in girls. The proportion of overweight was 14.8% in each group. Overweight adolescents had significantly higher weight z-scores at birth, 1.2 month, 3.3 months, 7.6 months, 1 year, 2 years, and 4 years of age as compared with normal-weight adolescents. There were significant positive associations of weight z-scores and conditional relative weights with adolescent BMI at all ages except birth, which were strongest after the first year of life. In a majority of overweight adolescents, overweight had manifested within the first 4 years of life. CONCLUSIONS: Greater than expected weigh gain at any time in the first years of life is associated with an increased BMI in adolescence. The effect is strongest after the first year.