Secular trend and urban–rural disparity for age at spermarche among Chinese Han boys from 1995 to 2019

Aim: To examine the secular trend and the urban–rural disparity of spermarche among Chinese Han boys from 1995 to 2019. Methods: A total of 392 775 boys of Han ethnicity aged 11–18 years were extracted from the 1995, 2000, 2005, 2010, 2014 and 2019 Chinese National Surveys on Students' Constitution and Health. The median age at spermarche was estimated using the status quo data and probit analysis. The chi-square, ANOVA and LSD tests were used to compare the differences between the year-subgroups. U-test was used to compare the difference between urban and rural areas at each year. Results: The median age at spermarche in Chinese Han boys decreased from 14.6 years in 1995 to 13.9 years in 2019 (p < 0.001). The rural boys showed a faster decreasing pace with a 1-year advance of age at spermarche while the urban boys had only a 0.5-year decrement, and there was still a statistically significant difference between urban–rural areas in 2019 (p < 0.001). Similar to urban–rural disparity, the age gap at spermarche between areas with different urbanisation rates became smaller over time. Conclusions: In general, spermarche in Chinese Han boys showed a decreasing trend, but the pace was slowing down. The urban–rural disparity in puberty development still existed but was gradually narrowing.