title: Declining sperm quality in New Zealand over 20 years.
abstract: OBJECTIVE
  To investigate whether semen quality has changed in New Zealand over the last 20 years.
  
  
  METHODS
  A retrospective study from 1987 to 2007. The sperm concentration, volume of seminal fluid, and the percentage of motile sperm were analysed from the first semen sample of 975 men presenting as sperm donors in Auckland and Wellington.
  
  
  RESULTS
  Linear regression showed that the mean concentration of sperm decreased from 110 x 10(6) per millilitre in 1987 to 50 x 10(6) per millilitre in 2007 (p<0.001); an average reduction of 2.5% annually. The volume of semen also fell significantly from 3.7 ml to 3.3 ml (p<0.001). There was no concomitant change in the duration of abstinence.
  
  
  CONCLUSIONS
  The decline in semen volume and sperm concentration in men presenting as sperm donors may indicate a reduction in the semen quality of New Zealand men over the past 20 years.
authors.affiliation: University of Auckland School of Medicine, Auckland, New Zealand.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Shine
authors.forename: John
authors.initials: J
authors.lastname: Peek
authors.forename: Mary
authors.initials: M
authors.lastname: Birdsall
mesh_terms: D000328:Adult; D005298:Fertility; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009520:New Zealand; D012189:Retrospective Studies; D055101:Semen Analysis; D013094:Spermatozoa / Q000502:physiology*