title: Effect of male age on fertility: evidence for the decline in male fertility with increasing age.
abstract: OBJECTIVE
  To evaluate the effect of men's age on time to pregnancy (TTP) using age at the onset of pregnancy attempts, adjusting for the confounding effects of women's age, coital frequency, and life-style characteristics.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Teaching hospital in Hull, United Kingdom.
  
  
  METHODS
  Two thousand one hundred twelve consecutive pregnant women.
  
  
  METHODS
  A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility, previous pregnancies, age, and individual life-style characteristics of both partners.
  
  
  METHODS
  Time to pregnancy, conception rates, and relative risk of subfecundity for men and women's age groups.
  
  
  RESULTS
  As with women's age, increasing men's age was associated with significantly rising TTP and declining conception rates. A fivefold increase in TTP occurred with men's age >45 years. Relative to men <25 years old, those >45 years were 4.6-fold and 12.5-fold more likely to have had TTP of >1 or >2 years. Restricting the analysis to partners of young women revealed similar effects of increasing men's age. Women >35 years were 2.2-fold more likely to be subfertile than women <25 years. The results were comparable, whether age at conception or at the onset of pregnancy attempts was analyzed, and they remained unchanged after adjustment for the confounding factors.
  
  
  CONCLUSIONS
  Evidence for and quantification of the decline in men's fertility with increasing age is provided.
authors.affiliation: The University of Hull, Post Graduate Medical Institute and Hull & York Medical School, Hull, United Kingdom. manhassan@yahoo.com
authors.forename: Mohamed A M
authors.initials: MA
authors.lastname: Hassan
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Killick
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D005260:Female; D005298:Fertility; D006801:Humans; D008297:Male; D008875:Middle Aged