Secular Trend in Reported Sperm Counts

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Abstract
Claims that there has been a recent secular decline in sperm counts have been disputed. Protagonists on both sides of the discussion have based their arguments on data from a few large samples tested at different times and (mostly) in different places. It is not disputed that the differences between the mean counts in the various samples are statistically significant: what is at issue is whether a secular decline is responsible. The present note adopts a different approach to the problem: an attempt was made to locate representative data on mean sperm counts of unselected men over the last 45 yr; 29 such means are cited here. There can be no reasonable doubt that these reported mean sperm counts show a decline with time of publication, at least since 1960. It is not easy to see what artifact, other than a real secular trend, might be responsible. At least in some places a secular decline has probably occurred.