title: Turning point of age for semen quality: a population-based study in Chinese men.
abstract: OBJECTIVE
  To explore the relationship between age and semen quality in Chinese men.
  
  
  METHODS
  Population-based cross-sectional study.
  
  
  METHODS
  The Department of Reproductive Epidemiology and Social Science, Shanghai Institute of Planned Parenthood Research, People's Republic of China.
  
  
  METHODS
  Healthy 20- to 60-year-old men.
  
  
  METHODS
  Standard World Health Organization procedures (3rd ed.) for semen analysis.
  
  
  METHODS
  Semen volume, sperm concentration, total sperm number, progressive motility, vitality, and sperm morphology.
  
  
  RESULTS
  Statistical analysis results of 998 subjects showed that age was negatively correlated with progressive motility, vitality, and percentage of normal sperm. No declining trend was found between age and parameters semen volume, sperm concentration, or total sperm number. Rapidly progressive motility and percentage of normal sperm began to decrease slowly at age 30 years, and progressive motility began to decrease at age 40 years. Compared with the 20- to 29-year age group, the values of the latter three parameters showed significant differences in men aged ≥35, ≥45, and ≥40 years.
  
  
  CONCLUSIONS
  Increasing age mainly influences sperm motility, vitality, and normal morphology, but these parameters have turning points at different ages. Because of the large sample size, this information can be used to provide standard values for Chinese men, particularly in the age range 30-50 years. Further research would enroll a large sample of healthy 40- to 70-year olds to examine declining semen parameters in these age groups.
authors.affiliation: Department of Reproductive Epidemiology and Social Science, National Population and Family Planning Key Laboratory of Contraceptive Drugs and Devices, Shanghai, People's Republic of China.
authors.forename: Qian-Xi
authors.initials: QX
authors.lastname: Zhu
authors.forename: Catherine
authors.initials: C
authors.lastname: Meads
authors.forename: Min-Li
authors.initials: ML
authors.lastname: Lu
authors.forename: Jun-Qing
authors.initials: JQ
authors.lastname: Wu
authors.forename: Wei-Jin
authors.initials: WJ
authors.lastname: Zhou
authors.forename: Er-Sheng
authors.initials: ES
authors.lastname: Gao
mesh_terms: D000328:Adult; D017677:Age Distribution; D000375:Aging / Q000473:pathology / Q000502:physiology*; D044466:Asian People / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012661:Semen / Q000166:cytology*; D013076:Sperm Count / Q000706:statistics & numerical data*; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology* / Q000502:physiology; D055815:Young Adult