National estimates of pubertal milestones among urban and rural Chinese boys.

AIM: To provide up-to-date pubertal characteristics in a representative population of boys from both urban and rural areas of China.

SUBJECTS AND METHODS: The China Puberty Research Collaboration enrolled 15 011 boys of Chinese Han ethnicity aged 6.0-18.9 years in eight regions including both urban and rural areas. Stages of genital and pubic hair development were assessed by trained physicians according to the Tanner method. Testicular volume was evaluated with a Prader orchidometer.

RESULTS: Median age for onset of testicular volume of 4 mL or greater was 11.02 years. Median age for onset of genital (G2), pubic hair development (PH2) and spermarche was 11.24 years, 12.67 years and 14.32 years, respectively. Boys with BMI ≥ 85th percentile reached the onset of TV ≥ 4 ml (11.09 years), G2 (11.34 years) and G3 (13.01 years) later than boys with a normal BMI (10.95 years, 11.1 years and 12.88 years, respectively). Urban boys achieved pubertal milestones at an earlier age than rural peers except for G5 (13.4 vs 13.76 years) and PH5 (12.86 years vs 13.14 years).

CONCLUSIONS: There is an asynchronous pattern in the onset of puberty among Chinese boys. Higher BMI is related to early pubertal onset but fast pubertal progression. Urban boys achieved onset of puberty earlier than rural boys in China.