title: Paternal age and reproduction.
abstract: BACKGROUND
  Due to various sociological factors, couples in developed countries are increasingly delaying childbearing. Besides ethical, economical and sociological issues, this trend presents us with several complex problems in reproduction. Although it is well-known that maternal age has a negative effect on fertility and increases the risk of adverse outcome during pregnancy and in offspring, the paternal influence on these outcomes is less well researched and not well-known.
  
  
  METHODS
  We performed a systematic search of PubMed, and retrieved original articles and review articles to update our previous survey in this journal.
  
  
  RESULTS
  This review highlights the link between male age and genetic abnormalities in the germ line and summarizes the knowledge about the effects of paternal age on reproductive function and outcome. Increasing paternal age can be associated with decreasing androgen levels, decreased sexual activity, alterations of testicular morphology and a deterioration of semen quality (volume, motility, morphology). Increased paternal age has an influence on DNA integrity of sperm, increases telomere length in spermatozoa and is suggested to have epigenetic effects. These changes may, at least in part, be responsible for the association of paternal age over 40 years with reduced fertility, an increase in pregnancy-associated complications and adverse outcome in the offspring.
  
  
  CONCLUSIONS
  Although higher maternal age can be an indication for intensive prenatal diagnosis, including invasive diagnostics, consideration of the available evidence suggests that paternal age itself, however, provides no rationale for invasive procedures.
authors.affiliation: Centre of Reproductive Medicine and Andrology of the University, Muenster, Germany.
authors.forename: Gideon A
authors.initials: GA
authors.lastname: Sartorius
authors.forename: Eberhard
authors.initials: E
authors.lastname: Nieschlag
mesh_terms: D000367:Age Factors; D002869:Chromosome Aberrations; D005260:Female; D005298:Fertility; D006728:Hormones / Q000378:metabolism; D006801:Humans; D008297:Male; D010331:Paternal Age; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D011256:Pregnancy Outcome / Q000453:epidemiology / Q000235:genetics; D055101:Semen Analysis; D012959:Socioeconomic Factors; D013737:Testis / Q000473:pathology
chemical_list: D006728:Hormones