Objective  To study the relationship between obesity and the age of spermarche among Han boys and to provide evidences for researches on adolescents′ growth and development.

  Methods  We extracted data on height, weight, and spermatorrhea of 3 893 Chinese Han boys aged 11 – 18 years from the dataset of a physique and health survey conducted in Hubei province in 2014. Body mass index (BMI) of the boys was calculated for the evaluation of nutrition status; probit regression was adopted to estimate median age at spermarche; and U-test was applied in comparison of urban-rural differences in median age at spermarche among the boys.

  Results  Among the Han boys, the overweight and obesity rate were 14.85% and 6.65%; the overweight and obesity rate were significantly higher among the urban boys than among the rural boys (17.43% vs. 12.36%, χ² = 19.74 and 9.47% vs. 3.94%, χ² = 48.01; both P < 0.05). The reported rate of spermarche was 19.75% and 3.42% among the obese and normal weight urban boys aged 12 years; the reported rate of spermarche was 86.96% and 41.18% among the obese and undernourished urban boys aged 14 years, while the rate was 70.26% and 21.74% among the normal weight and undernourished rural boys aged 14 years; and the reported rate of spermarche was 66.67% and 95.93% among the obese and undernourished urban boys aged 17 years. There was a significant disparity in the reported rate of spermarche between the boys with different nutritional conditions for all the 4 boy groups, with chi-square values of 10.70, 9.34, 21.33, and 20.64, respectively (all P < 0.05). The median age at spermarche of the urban boys was significantly higher than that of the rural boys (13.75 years vs. 13.65 years, P < 0.05).

  Conclusion  To some extent, obesity is associated with the age at spermarche, but further studies on the issue are needed.