A recently published meta-analysis shows that global sperm counts are declining worldwide—at an accelerating rate.

 

The article, published in the journal Human Reproduction Update in November 2022 by an international team of researchers, reviewed 2,936 scholarly abstracts and 868 full articles and analyzed data from 38 sperm count studies done on six continents, updating their landmark study of 2017.

The 2017 study found sperm counts had fallen in North America, Europe, and Australia by over 50 percent in a fifty-year span. The current study updated this data as well as added data from South/Central America, Asia, and Africa.

“The aim of this study was to examine trends in sperm count among men from all continents. The broader implications of a global decline in sperm count, the knowledge gaps left unfilled by our prior analysis, and the controversies surrounding this issue warranted an up-to-date meta-analysis,” said the authors.

The analysis found that while sperm counts had declined at the average rate per year of 1.16 percent between 1972 and 2000, the rate of decline since 2000 has increased to an average of 2.64 percent per year.

The new 2022 study updates an earlier 2017 study to cover a broader geographic area and include new studies. Its analysis reveals a significant drop in sperm count. (Temporal trends in sperm count: a systematic review and meta-regression analysis of sampl

Reviewing the findings in an After Skool YouTube episode, study author Shanna Swan said:

“Now we can conclude that among men who didn’t know what their fertility [rate] was, who are, by the way, most representative of the general population, that there was a significant decline [in sperm counts and sperm concentration] in Asia, Africa, and South America—so now we can say that our finding of a significant decline in sperm concentration and count is worldwide—that was a big change from the 2017 paper.

“The other change from the 2017 paper was the rate at which sperm counts are declining: When we look at recent years—particularly since the turn of the century—the rate is 2.64 per year. That’s more than double 1.16, the prior finding.”

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The obvious question is—why the accelerated rate of decline?

Swan dismissed genetic explanations, pointing out that genetic changes take “many generations to appear” whereas these changes are taking place in two generations or less.

“That leaves us with environment,” Swan said.

Swan and other experts believe the problem is a class of chemicals called endocrine disruptors, which interfere with the body’s hormones.

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