title: The association of age and semen quality in healthy men.
abstract: BACKGROUND
  Although the effect of maternal age on fertility is well known, it is unclear whether paternal age also affects fertility. This cross-sectional study sought to characterize the association between age and semen quality, a well-known proxy of fertility status.
  
  
  METHODS
  A convenience sample of 97 non-smoking men (aged 22-80 years) without known fertility problems was recruited from a national government laboratory. The men provided semen samples and information relating to lifestyle, diet, medical and occupational details. Semen volume (ml), sperm concentration (x10(6)/ml), total sperm count (x10(6)), motility (%), progressive motility (%) and total progressively motile sperm count (x10(6)) were measured.
  
  
  RESULTS
  After adjusting for covariates, semen volume decreased by 0.03 ml per year of age (95% CI: -0.05, -0.01); motility decreased by 0.7% per year (95% CI: -0.92, -0.43); progressive motility decreased by 3.1% per year (95% CI: -4.5, -1.6); and total progressively motile sperm count decreased by 4.7% per year (95% CI: -7.2, -2.2). There was a suggested decrease in sperm concentration and count. The proportion of men with abnormal volume, concentration and motility was significantly increased across the age decades.
  
  
  CONCLUSIONS
  In a convenience sample of healthy men from a non-clinical setting, semen volume and sperm motility decreased continuously between 22-80 years of age, with no evidence of a threshold.
authors.affiliation: School of Public Health, University of California, Berkeley, CA, USA.
authors.forename: B
authors.initials: B
authors.lastname: Eskenazi
authors.forename: A J
authors.initials: AJ
authors.lastname: Wyrobek
authors.forename: E
authors.initials: E
authors.lastname: Sloter
authors.forename: S A
authors.initials: SA
authors.lastname: Kidd
authors.forename: L
authors.initials: L
authors.lastname: Moore
authors.forename: S
authors.initials: S
authors.lastname: Young
authors.forename: D
authors.initials: D
authors.lastname: Moore
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012661:Semen / Q000166:cytology* / Q000502:physiology*; D013076:Sperm Count; D013081:Sperm Motility