title: Secular trends in sperm variables for groups of men in fertile and infertile couples.
abstract: OBJECTIVE
  To assess possible secular trends in sperm variables in men according to previous or subsequent paternity.
  
  
  METHODS
  A comparison of secular trends in sperm variables 1975-1994 in men under investigation for infertility in groups according to previous and subsequent paternity, based on data from the Medical Birth Registry of Norway.
  
  
  METHODS
  University hospital, Sperm laboratory and the Medical Birth Registry of Norway.
  
  
  METHODS
  Samples were obtained from: 1108 men who had fathered at least one child before the analysis. 1786 men who had at least one child after the analysis, and 2286 men with no children registered.
  
  
  METHODS
  Sperm concentration, seminal fluid volume, total number of spermatozoa per ejaculate.
  
  
  RESULTS
  Analyzed by year of evaluation, men with no child registered had a significant secular decrease of sperm concentration, total number of sperms per ejaculate and seminal volume. The group with subsequent children had significant secular decrease of sperm concentration and total sperm count per ejaculate, while no significant changes were found for the group with previous children. Analyzed by year of birth, a significant decrease of sperm concentration and total sperm count was found for the group without and for the group with subsequent children.
  
  
  CONCLUSIONS
  The results are compatible with a cohort effect, exhibiting a trend of deteriorating sperm variables in consecutive birth cohorts.
authors: Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
authors: M
authors: M
authors: Ulstein
authors: A
authors: A
authors: Irgens
authors: L M
authors: LM
authors: Irgens
mesh_terms: D000328:Adult; D015988:Cohort Effect; D005260:Female; D006801:Humans; D007248:Infertility, Male / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D012661:Semen; D013076:Sperm Count; D013094:Spermatozoa