Onset of Puberty: Younger Still

Investigators examined age of puberty onset in a U.S. longitudinal study of 1239 racially and ethnically diverse girls aged 6 to 8 years at enrollment at 3 study sites (New York City, Cincinnati, and San Francisco). The investigators developed a standardized protocol for pubertal staging based on the Tanner criteria for breast development.

Trained researchers were instructed to inspect and palpate for the presence of breast tissue. Overall, 10.4% of whites, 23.4% of blacks, and 14.9% of Hispanics showed evidence of breast development (Tanner stage ≥2) at age 7 years. Only 1 of 45 Asian girls had breast development. In logistic regression analysis, breast development was significantly associated with higher body-mass index percentile, older a…