[Is male fertility declining?].
In the lay press, a worldwide decline in male fertility is often accepted. In fact, this assumption is based on a meta-analysis of "normal sperm parameters" in the medical literature between 1938-1998 and based on retrospective studies from several centers. Other studies, however, have not shown a decrease of sperm parameters. Some have even shown an increase of sperm parameters. Some have even shown an increase of sperm parameters. A critical analysis of all these studies shows great differences between studies in selection of normal men, measurement of sperm parameters, analysis of data, ... Also, unexplained geographical differences in sperm density exist that may influence the analysis. In conclusion, a worldwide decline of sperm quality or male fertility has not been scientifically proved.
Endocrinologie-Andrologie UZ, Gasthuisberg, Leuven.
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Vanderschueren
D005298:Fertility / Q000502:physiology*; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D015203:Reproducibility of Results; D012189:Retrospective Studies
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