title: Data from men in greater Seattle area reveals no downward trend in semen quality: further evidence that deterioration of semen quality is not geographically uniform.
abstract: OBJECTIVE
  To determine whether there has been a decline in semen quality in a group of healthy men during the past 21 years.
  
  
  METHODS
  Retrospective analysis of the relationship between time and changes in semen parameters over 21 years using regression analysis.
  
  
  METHODS
  A tertiary university center.
  
  
  METHODS
  Five hundred ten healthy, normal men who donated multiple semen samples as participants in clinical studies between 1972 and 1993.
  
  
  METHODS
  Sperm concentration, semen volume, total numbers of sperm per ejaculate, and percent spermatozoa with normal morphology.
  
  
  RESULTS
  There was no decrease in sperm concentration, semen volume, total number of sperm per ejaculate, and percent normal sperm morphology in 510 healthy men studied between 1972 and 1993.
  
  
  CONCLUSIONS
  We conclude that in this population of healthy young men there has not been any decline in semen quality in the past 21 years.
authors.affiliation: Department of Medicine, University of Washington, Seattle, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Paulsen
authors.forename: N G
authors.initials: NG
authors.lastname: Berman
authors.forename: C
authors.initials: C
authors.lastname: Wang
mesh_terms: D005298:Fertility; D006801:Humans; D007248:Infertility, Male / Q000453:epidemiology; D008297:Male; D012044:Regression Analysis; D012189:Retrospective Studies; D012661:Semen / Q000502:physiology*; D013076:Sperm Count; D013094:Spermatozoa / Q000002:abnormalities; D013997:Time Factors; D014861:Washington