Age at spermarche: 15-year trend and its association with body mass index in Chinese school-aged boys

Background: Little is known about the secular trends in age at spermarche among boys, and the association between body mass index (BMI) and male puberty is controversial.

Objective: This study aimed to estimate the trend in age at spermarche in China and explore the association of spermarche with BMI.

Methods: We used four cross-sectional Chinese National Surveys on Students' Constitution and Health (CNSSCH; 1995, 2000, 2005 and 2010). Median age at spermarche was determined using probit analysis. Logistic regression was used to assess the association of spermarche with BMI.

Results: Age at spermarche among Chinese boys dropped from 14.57 to 14.03 years from 1995 to 2010 with a decrease of 4.3 months per decade. Boys with BMI-for-age z-score lower than -2 had the latest age at spermarche. A higher BMI or BMI-for-age z-score was associated with an increased likelihood of having reached spermarche, and this association was consistently observed at all survey points.

Conclusion: This study provides important evidence of a secular trend of earlier age at spermarche over the past 15 years in China, and this decrease was accompanied by a simultaneous increase in BMI. Strategies and interventions focusing on thinness may promote both their nutritional status and puberty development among Chinese boys.