[Testis volume, pubic hair development and spermarcheal age in urban Chinese boys].

OBJECTIVE

There is a trend that puberty is starting earlier in the 21st century, which is primarily based on studies of girls. The assessment of pubertal stages in the individual child is useful only if recent and reliable reference data from the same population are available for comparison. However, nationally representative pubertal data for Chinese boys in China are lacking. The aim of this study was to investigate the current pubertal development in healthy urban Chinese boys.

METHOD

A cross-sectional study of the pubertal development of a sample of 19,054 urban Chinese boys aged 3 - 19.83 years was conducted between 2003 and 2005. Testicular volume was determined with a Prader orchidometer. Pubic hair development was assessed according to the Tanner method. Data on spermarche were collected by the status quo method. Probit analysis was used to calculate the median age and 95% CI for onset of testicular and pubic hair development and spermarche. A testicular volume greater than or equal to 4 ml was taken as a definite sign of the onset of puberty. Mean ages for sexual development in boys were compared with other published series, while the spermarcheal age was compared to those in the similar population of the five National Surveys on Students Constitution and Health undertaken since 1979 in China.

RESULT

At the age of 9 years, 12.99% of the boys had a testicular volume 4 ml or more. The median age of onset of puberty as indicated by a testicular volume of 4 ml or more was 10.55 (95% CI 10.27 - 10.79) years. The median age for onset of pubic hair development (PH(2)) and spermarche was 12.78 (95% CI 12.67 - 12.89) years and 14.05 (95%CI 13.80 - 14.32) years, respectively. There was a highly significant downward secular trend for spermarcheal age of Chinese boys since 1979.

CONCLUSION

Pubertal onset as indicated by testicular development in urban Chinese boys is earlier than currently used norms. Age of testicular development is among the earliest medians recorded in the world population, while onset of pubic hair development is among the oldest ones. Secular downward change of sexual maturation as indicated by initiation of spermarche has been significant since 1979.