Trajectory of Body Mass Index from Ages 2 to 7 Years and Age at Peak Height Velocity in Boys and Girls

Objective: To examine the associations between body mass index (BMI) at 2-4 years and 5-7 years and age at peak height velocity (APHV), an objective measure of pubertal timing, among boys and girls from predominantly racial minorities in the US that have been historically underrepresented in this research topic. Study design: This study included 1296 mother–child dyads from the Boston Birth Cohort, a predominantly Black and low-income cohort enrolled at birth and followed prospectively during 1998-2018. The exposure was overweight or obesity, based on Centers for Disease Control and Prevention reference standards. The outcome was APHV, derived using a mixed effects growth curve model. Multiple regression was used to estimate the overweight or obesity–APHV association and control for confounders. Results: Obesity at 2-4 years was associated with earlier APHV in boys (B in years, −0.19; 95% CI, −0.35 to −0.03) and girls (B, −0.22; 95% CI, −0.37 to −0.07). Obesity at 5-7 years was associated with earlier APHV in boys (B, −0.18; 95% CI, −0.32 to −0.03), whereas overweight and obesity at 5-7 years were both associated with earlier APHV in girls (overweight: B, −0.24; 95% CI, −0.40 to −0.08; obesity: B, −0.27; 95% CI, −0.40 to −0.13). With BMI trajectory, boys with persistent overweight or obesity and girls with overweight or obesity at 5-7 years, irrespective of overweight or obesity status at 2-4 years, had earlier APHV. Conclusions: This prospective birth cohort study found that overweight or obesity during 2-7 years was associated with earlier pubertal onset in both boys and girls. The BMI trajectory analyses further suggest that reversal of overweight or obesity may halt the progression toward early puberty.