Secondary sexual characteristics and menses in urban Chinese girls

：Objective To determinethe current prevalence and mean ages of onset of pubertal characteristics in healthy urbanChinese girls. To obtain the up-to-date normal reference data for diagnosing abnormalpuberty such as precocious puberty and pubertal delay. Methods A cross-sectional study ofsexual maturation of healthy urban Chinese girls was conducted in 9 representative citiesof the eastern, western,southern, and northern parts and central region of China between2003 and 2005. At examination, stages of breast and pubic hair development were rated ingirls aged 3 to 19. 83 years, and height and weight were also recorded. Data on menseswere collected by the status quo method. Probit analysis was used to calculate the medianage and 95% confidence interval (CI) for onset of breast and pubic hair development andmenarche.Comparison of the mean ages for sexual development was made with other publishedseries. Comparison of the age of menarche was also made with the five similar studies donein China in the past 25 years. Results Data were analyzed in 20 654 apparently healthygirls. At age 8 years, 19.57% of these girls had evidence of breast development. Themedian ages of onset of Tanner stages 2 and 3 for breast development were 9.20 (95%CI:9.06-9.32) years and 10.37 (95% CI: 10.28-10.45) years, respectively. The median agesof onset of Tanner stages 2 and 3 for pubic hair development were 11.16 ( 95% CI:11.03-11.29 ) years and 12.40 (95% CI:12.25-12.55) years, respectively. Menses occurred at12.27 years (95% CI: 12.16-12.39). Urban Chinese girls are experiencing breast developmentat young ages, among the earliest recorded worldwide. A significant downward secular trendof menarcheal age was observed since 1979. Conclusions These data suggest that urbanChinese girls are actually experiencing earlier breast development than currently usednorms. The up-to-date reference for normal pubertal development in urban Chinese girlsneeds to be established for the purpose of determining precocious puberty or pubertaldelay.