title: [Study of geographic distribution and 10 years' change of spermarche in Chinese boys of Han-group aged 11 to 18].
abstract: OBJECTIVE
  To analyze the geographic distribution and 10 years' change of spermarche in Chinese boys of Hangroup aged 11 - 18.
  
  
  METHODS
  Calculate the average age of spermarche of Chinese boys who participated in National Physical Fitness and Health Surveillance in 2005 and 1995. The sample size of boys was 69 320 in 2005, 68 992 in 1995 National Physical Fitness and Health Surveillance, respectively. The geographic distribution of Chinese boys were categorized into 6 areas as north, northeast, east, south central, southwest and northwest by administrative divisions.
  
  
  RESULTS
  The average ages at spermarche were 13.98 and 14.22 years old for urban and rural boys in 2005, respectively. The average ages at spermarche were 13.57 and 13.72 years old for urban and rural boys who living in southwest of China. And the average ages at spermarche were 14.18 and 14.39 years old for urban boys who lived in northwest of China, and rural boys who lived in south central of China, respectively. The average age of spermarche of the top 5 provinces were Chongqing (13.28), Guizhou (13.47), Hainan (13.47), Sichuan (13.56) and Tianjin (13.61); and the last 5 provinces were Hubei (15.30), Qinghai (15.13), Liaoning (14.75), Guangxi (14.68) and Shanghai (14.55). The average ages of spermarche were 14.43 and 14.77 years old for urban and rural boys in 1995, respectively, and thus the ages of spermarche in 2005 were 0.45 and 0.55 years earlier than that of urban and rural boys in 1995.
  
  
  CONCLUSIONS
  There was a large variation among different geographic areas. The onset of spermarche was generally earlier in urban than in rural boys, the earliest in southwest of China, and the latest in northwest and south central of China. Significant decline trend of age at spermarche could be found in Chinese boys, especially in rural areas.
authors.affiliation: The Institute of Child and Adolescent Health, Peking University Health Science Center, Beijing 100191, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Song
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.forename: Pei-jin
authors.initials: PJ
authors.lastname: Hu
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D044466:Asian People; D002648:Child; D002681:China / Q000453:epidemiology; D004542:Ejaculation; D006801:Humans; D008297:Male; D011627:Puberty; D012424:Rural Population; D012741:Sexual Maturation; D014505:Urban Population