Five years ago, a study describing a precipitous decline in sperm count raised concerns about the end of procreation as we know it. Now new work shows that fertility has declined further and the rate of decline is accelerating, raising fears of a looming global fertility crisis.
The international team led by Hagai Levineof the Hebrew University of Jerusalem Hadassah Braun School of Public Health, and Shanna Swan, of the Icahn School of Medicine, Mount Sinai (USA) together with researchers from Denmark, Brazil, Spain, Israel and the USA, now publishes the first meta-analysis to demonstrate decreased sperm count among men of South and Central America, Asia and Africa.
The initial study, published in July 2017, revealed that sperm count (the number of sperm in a single ejaculation) se plummeted by more than 50% among men in North America, Europe, Australia, and New Zealand between 1973 and 2011. Since then, a team led by the same researchers has explored what has happened in the past 10 years.
Now, in this new work, they alarmingly find that the decline in sperm counts in North America, Europe and Australia, reported by this team in 2017, has continued and even accelerated in the 21st century.
The number of sperm It is not just an indicator of human fertility; It is also an indicator of the men’s health, as low levels are associated with increased risk of chronic disease, testicular cancer, and shorter life expectancy. The authors say the decline reflects a global crisis related to our modern environment and lifestyle, with broad implications for the survival of the human species.
This latest analysis, using data from 53 countries, is published today in the journal Human Reproduction Update. It includes an additional seven years of data collection (2011-2018) and focuses on sperm count trends among men in regions not previously reviewed, specifically South America, Asia, and Africa.
The data shows, for the first time, that men from those regions share the significant decline in total sperm count (TSC) and sperm concentration (SC) previously seen in North America, Europe and Australia. Furthermore, this study shows an accelerating decline after 2000 in TSC and SC globally.
The decline reflects a global crisis related to our modern environment and lifestyle, with broad implications for the survival of the human species.
“We are seeing a significant global decline in sperm count of more than 50% in the last 46 years, a decline that has accelerated in recent years,” Levine said.
While the current study did not examine the causes of decreased sperm counts, Levine pointed to recent research indicating that alterations in reproductive tract development during fetal life are linked to impaired fertility throughout life. and other markers of reproductive dysfunction. Furthermore, Levine explained that “lifestyle choices and chemicals in the environment are negatively affecting this fetal development.”
Time is running out, Levine warned. “Our findings serve as a canary in a coal mine. We have a serious problem on our hands that, if not mitigated, could threaten the survival of humanity. We urgently call for global action to promote healthier environments for all species and reduce exposures and behaviors that threaten our reproductive health.”
Swan emphasized that Low sperm counts not only affect men’s fertility, but have serious ramifications for men’s health in general, and are linked to other adverse trends, collectively known as testicular dysgenesis syndrome. “The concerning declines in men’s sperm concentration and total sperm count by more than 1% each year, as reported in our article, are consistent with adverse trends in other men’s health outcomes, such as testicular cancer, hormonal alteration and congenital genital defects, as well as deterioration of female reproductive health. This cannot continue unchecked.”
We have a serious problem on our hands that, if not mitigated, could threaten the survival of humanity.
Levine calls the results “worrying, as we expected the decline to level off at some point. The opposite may be true, and we may cross a tipping point when the majority of men will be subfertile or when the causes of this decline will also be manifested by other adverse health trends.”
Neither this paper nor the 2017 meta-analysis have examined what is causing this drop, but some research suggests environmental and lifestyle factors may be to blame.. These include exposure to endocrine-disrupting chemicals (which mimic or interfere with the body’s hormones), smoking, and obesity.
The fact that sperm count declines are also occurring in countries in South and Central America, Africa and Asia, according to the new meta-analysis, suggests that lifestyle factors and environmental exposures are likely to be to blame. around the world, Swan says.