by Researchers are sounding the alarm that falling sperm counts “threaten the survival of humanity” – yet experts remain cautious about the findings of a new study.
A controversial paper recently published in the journal Human Reproduction Update found that sperm counts worldwide have declined by about half since the 1970s — and the trend has accelerated since the year 2000.
“It is the first study to examine global trends in semen quality in recent years and the first to show declining sperm counts in men from South and Central America, Asia and Africa,” said lead author Hagai Levine, a professor at Hadassah’s Hebrew University of Jerusalem Braun School of Public Health.
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However, many experts in the scientific community remain skeptical about the results.
“The Levine group’s conclusions – that sperm concentrations are declining worldwide and that the decline has been accelerating – are not shared by many in the andrology community,” said Dr. John K. Amory, professor of medicine at the University of Washington School of Medicine in Seattle.
A doctor wearing blue latex gloves holds a plastic container with biological material. “Over time, more data will be needed to fully understand these phenomena,” a medical professor told Fox News Digital.
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“Furthermore, the mean sperm concentrations observed in these studies remain well within the range of values thought to be consistent with normal male fertility,” Amory said.
He also said, “More data will be needed over time to fully understand these phenomena.”
What did the study show?
Levine’s international team from Denmark, Brazil, Spain, Israel and the United States conducted a meta-analysis combining results from more than 250 previous studies from 53 countries including the United States between 1973 and 2018.
“This meta-analysis examines global trends in sperm concentration (SC) and total sperm concentration (TCS) between 1973 and 2018,” Levine told Fox News Digital.
The study concluded that sperm concentration is declining worldwide not only in North America, Europe and Australia, but also in South and Central America, Africa and Asia.
The present study builds on previously published 2017 data on sperm counts in North America, Europe and Australia.
She examined seven additional years of data from 2011 to 2018 to focus on regions of the world not examined in her first study – South and Central America, Asia and Africa.
Levine noted that the study found that sperm concentrations have dropped by more than half worldwide, with a 62% drop in total sperm concentrations between 1973 and 2018.
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“We found that the rate of decline has increased from 1.2% each year since 1972 to 2.6% each year since 2000,” Levine noted.
“The increased power of data and statistics allowed us, for the first time, to analyze trends in the 21st century. [up to] 2018.”
The authors pointed out the limitations of the study because they only analyzed the participants’ sperm count and concentration – not how the sperm moved or their shape.
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The study concluded that sperm concentration is declining worldwide not only in North America, Europe and Australia, but also in South and Central America, Africa and Asia.
What does falling sperm count mean?
“Sperm count is an indicator of men’s overall health, with low levels being associated with an increased risk of chronic disease, testicular cancer and a shortened lifespan,” Levine told Fox News Digital.
“On a larger scale, the decline means a global problem related to modern environment and lifestyle, reflecting a disrupted diseased world, at least for human reproduction.”
“Fortunately, the methods of counting sperm are fairly simple and haven’t really changed in the last 50 years.”
However, sperm counts alone are not a good indicator of infertility because they must be viewed in the context of a couple — namely, how they interact with the egg and the female reproductive tract, according to the New York Times.
Sperm also grow from stem cells in the testicles, but development can take around two months, so a sperm count is only a “snapshot” of time, The Times also noted.
What is the controversy surrounding the paper?
The authors pointed out the limitations of the study because they only analyzed the participants’ sperm count and concentration – not how the sperm moved or their shape.
These are qualities that infertility specialists use to assess reproductive potential.
Researcher uses a microscope. “As [with] With any study, we’re limited by the fact that we see what we see,” lead author Levine told Fox News Digital.
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“The authors of this paper have performed a very elegant meta-analysis and I have no criticism at all of the way they have done so,” said Allan Pacey, Professor of Andrology at the University of Sheffield in the UK.
But Pacey told Fox News Digital he was “concerned” about the quality of the data on which the study’s analysis was based.
“The quality of the meta-analysis is as good as the original data we have, as noted by Prof. Pacey,” Levine told Fox News Digital.
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“Fortunately, the methods of counting sperm are fairly simple and haven’t really changed in the last 50 years.”
The paper states that “hemocytometer counting is the classic way of assessment [sperm count] and has been endorsed by the World Health Organization in all versions of the organization’s semen analysis manuals.”
But Pacey said counting sperm, even with the “gold standard” technique of hemocytometry, “is really difficult.”
“I think we’ve just gotten better over time because we’ve developed training and quality control programs around the world,” added Pacey.
“We can summarize that there is strong evidence of global decline, including in Latin America, Asia and Africa, but we cannot rely on any particular population or country.”
“I still think that’s a lot of what we’re seeing in the data.”
Levine told Fox News Digital, “Nevertheless, like [with] any study, we are limited by the fact that we see what we see.”
“We had 41 estimates [data from studies] from the US, but only one from Israel or one from Cuba – and some countries are not represented at all,” he added.
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“So we can summarize that there is strong evidence of global decline, including in Latin America, Asia and Africa, but we cannot be sure for any particular population or country.”
He explained that more studies are needed to monitor seed quality and better understand the causes of the decline.
Current world population
The study comes after a recent United Nations report found that “world population continues to grow, but the pace of growth is slowing”.
“In 2020, the global population growth rate fell below 1 percent per year for the first time since 1950.”
On November 15, 2022, the world population is estimated at 8 billion.
“In 2020, the global population growth rate fell below 1 percent per year for the first time since 1950.”
Why does the sperm count go down?
Although the study didn’t examine the cause of the drop in sperm count, Levine suggested that our modern environment and lifestyle play a role.
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“We have previously shown that disturbances in [the] The male reproductive system is dictated by prenatal exposure to environmental chemicals as well as poor health behaviors in adulthood,” Levine said.
“The study should serve as a wake-up call for clinicians, researchers, governments and the public to address the reduced sperm crisis by investing in research into unknown causes and mitigating known causes.”
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Still, Pacey remains “on the fence” about the results.
“The problem is that there is the idea of a drop in sperm count [gotten] into popular culture and therefore it is very difficult to have an impartial debate on the subject – even among scientists.”
