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

Abstract

To assess the time point during infancy and early childhood at which greater than expected weight gain is associated with overweight in adolescence. Current height, weight, and body mass index (BMI) were assessed in 1520 adolescents (mean age of boys, 15.52±0.84years; mean age of girls, 15.37±0.77years). 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. 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, 1.2month, 3.3months, 7.6months, 1year, 2years, and 4years 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 4years of life. 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.