Early overweight and pubertal maturation--pathways of association with young adults' overweight: a longitudinal study.

OBJECTIVE: Objectives of this study were to examine the prospective association of childhood body mass index (BMI) and overweight and pubertal stages with BMI and overweight in early adulthood independent of each other.

DESIGN: A population-based prospective birth cohort.

SUBJECTS: We used a population-based prospective birth cohort of 2897 (52% men) young adults who were born during 1981-1983 in Brisbane, Australia, and for whom we had puberty stages using Tanner scale at 14 years and measured BMI at 5 years of age.

MAIN OUTCOME MEASURES: Pubertal stages at adolescent and BMI and its categories at 21 years.

RESULTS: We found that increasing BMI and overweight at 5 years of age predict the advanced stages of puberty. An advanced stage of puberty predicts young adults' BMI and overweight status at 21 years. When taking both childhood BMI and pubertal status into consideration, we found that being overweight at 5 years substantively increases BMI at 21 years, regardless of the stage of puberty reported at 14 years. We also found that subjects with normal BMI at 5 years but with higher stages of puberty at 14 years had threefold greater risk to be overweight at 21 years compared with their counterparts. All associations remained consistent after controlling for potential confounders.

CONCLUSIONS: Although this study underscores the impact of both child overweight and pubertal development on young adults' obesity, the mechanism that further explains the impact of puberty needs to be identified.