Reproduction and extinction: Male sperm count halved in 45 years

The world's sperm count has halved in the past 45 years, according to a study published Nov. 15 in the journal Human Reproduction Update and reported by the Guardian . The study was conducted by an international team of researchers led by Professor Hagai Levine of the Hadassah Braun School of Public Health at the Hebrew University of Jerusalem.

The aim was to look at sperm count trends among men on all continents and analyzed 223 studies based on sperm samples taken from more than 57,000 men in 53 countries, including the United States, Europe and Australia, between the 1973 and 2018.

Previously, a 2017 study by the same team of researchers looked at sperm count data in North America, Europe, Australia and New Zealand. The new analysis updates that revision by including data from Central and South America, Asia and Africa for the first time.

Researchers in the latest study found a "significant decline" in sperm counts over that period. Specifically, they found that men in South America, Asia and Africa shared similar declines in total sperm count and concentration, as had previously been observed in their study focused on Europe, North America and Australia. So it doesn't seem like there's a racial or demographic factor.

Collectively, the results showed that the average sperm count decreased by 51.6% between 1973 and 2018 in men across all continents, declining by an average of 1.2% per year from an estimated 101. 2 million per milliliter to 49 million per milliliter from 1973 to 2018. During the same period, total sperm count decreased by 62.3%.

According to the Mayo Clinic, men are thought to have low sperm counts if they have fewer than 15 million sperm per milliliter or fewer than 39 million total sperm per ejaculate.

In addition, the researchers found that data for the year 2000 showed a decline in sperm concentrations of more than 2.6% per year, doubling from the previous decline of 1.16% per year in 1972.

The researchers said the "substantial and persistent decline is now recognized as a significant public health concern" and that more research into the causes of the decline is urgently needed to prevent further male reproductive health disorders.

"We hope that the new evidence provided here will receive the attention not only of clinicians and scientists, but also of decision makers and the general public," the researchers wrote.

Men suffering from infertility were excluded from the study.

However, the researchers noted limitations in their study, including the way the data was collected and reported, as standards and methods for counting sperm have changed dramatically over time. This makes it more difficult to compare the most recent counts to historical data. Furthermore, the researchers observed that complete elimination of all selection/recruitment bias was impossible because they were unable to collect sperm samples at random.

“I think this is another sign that something is wrong with the world and that we need to do something. So yes, I think this is a crisis that is best addressed now, before it reaches a tipping point that may not be reversible,” Levine, lead author of the research, told the Guardian. Of course, if the trend continues in this way, the path to extinction of the human race is open.

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The article Reproduction and extinction: the number of male sperm has halved in 45 years comes from Scenari Economici .

This is a machine translation of a post published on Scenari Economici at the URL on Wed, 23 Nov 2022 13:00:51 +0000.