Age of first spermatorrhea in Chinese adolescents,1980-2013:a meta analysis

Objective To analyze the change in the age at first spermatorrhea among adolescents in China.Methods Totally 74 relevant literatures published between 1980 and 2013 were retrieved via computer and manual searches;the literatures presented 192 sets of data collected among 434 992 people aged 6-21 years in all provinces,municipalities and autonomous regions of China,except for Tibet Autonomous Region,Hong Kong Special Administrative Region,and Macao Special Administrative.Meta-analysis was adopted in the study.Results During the 34 years,the age at the first spermatorrhea in Chinese adolescents declined significantly by 1.40 years from 15.09 years in 1980's to 13.78 years in 2013 (y=-0.042 4x+99.129,R²=0.3268,P<0.01),with an average age of 14.40 years.The average age at first spermatorrhea was reversely correlated with the years among the adolescents in both the north and south areas of China (both P<0.0001),with the decreased average years of 1.16 years and 1.33 years for the adolescents in the south and north areas of China.The adolescents in the north areas had a significantly elder age at first spermatorrhea (P<0.001) but a greater decline in the average age than those in the south areas.For the adolescents in a same area,those in the cities showed a younger age at first spermatorrhea than the adolescents in countryside;while the rural adolescents presented a greater decline in the age of first spermatorrhea than the urban adolescents (1.39 years vs.0.91 year).There were significant interactions in the impacts of different periods of time (every 10 years) and residential area (urban vs.rural and the south vs.north) on the age at first spermatorrhea among the adolescents (P<0.001).Conclusion Between 1980 and 2013,The age at first of spermatorrhea declined significantly and influenced interactively by period of time and residential area,urban and rural difference among Chinese adolescents between 1980 and 2003.