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.