Secondary Sexual Characteristics in Boys

and Mexican American boys were 12.0 (95% confidence interval [CI], 11.7-12.3), 11.2 (95% CI, 10.911.4), and 12.3 (95% CI, 12.1-12.6) years, respectively, and at stage 2 for genital growth were 10.1 (95% CI, 9.610.6), 9.5 (95% CI, 8.9-10.0), and 10.4 (95% CI, 9.611.1) years, respectively. All 3 groups were significantly taller and heavier than boys in previous NHANES reports and showed earlier genital maturation and pubic hair growth than previous studies based on Tanner staging. Statistically significant differences among the 3 racial/ ethnic groups were found in the median ages of onset of pubic hair growth and genital development at stage 5 with and without controlling for height and weight, indicating an earlier age of attainment for the African American boys. Conclusions: The median (mean) ages at the onset of genital and pubic hair growth were younger than in past studies. Additional studies are required to further evaluate these findings and to explore the public health implications. Arch Pediatr Adolesc Med. 2001;155:1022-1028