Sperm counts globally have fallen at an alarming rate – dropping by more than 62% between 1973 and 2018 – and could lead to a reproductive crisis, new research has found.
During the same period, the concentration of sperm among men dropped by more than 51%, from 101.2 million to 49 million sperm per milliliter of semen, according to the peer-reviewed study published Tuesday in the journal Human Reproduction Update.
That number is still above the World Health Organization’s cutoff, namely 15 million per milliliter, below which men are deemed to have a low sperm concentration, The Times of Israel reported.
But the drop is still alarming, according to Prof. Hagai Levine of the Hebrew University of Jerusalem, who led the study along with Prof. Shanna Swan at New York’s Icahn School of Medicine.
“We have a serious problem on our hands that, if not mitigated, could threaten mankind’s survival,” the epidemiologist said in a statement, adding that the findings serve as “a canary in a coal mine.”
The Israeli and American team, joined by researchers in Denmark, Brazil and Spain, studied sperm count trends in areas that had not been reviewed previously.
Levine noted that the news doesn’t address what is causing the declines, but other researchers have tied falling sperm counts to obesity, sedentary lifestyles, smoking, exposure to certain chemicals and pesticides, among other factors.
In 2017, the same team had already reported about an alarming decline in sperm counts across the Western world, according to Euronews.
It reported that sperm counts in America, Europe, Australia and New Zealand plummeted by more than 50% between 1973 and 2011.
The new study — which includes seven more years of statistics — is far wider in geographical reach, covering 53 countries, and its meta-analysis looked at 223 studies based on sperm samples from more than 57,000 men.
The research also sounds alarm bells for both male fertility and for men’s health in general because low sperm counts are associated with increased risk of chronic disease, testicular cancer and a decreased lifespan, the researchers noted.
We should be amazed and worried by the finding,” Levine told The Times of Israel.
“The trend of decline is very clear. This is a remarkable finding and I feel responsible to deliver it to the world. The decline is both very real and appears to be accelerating,” he told the news outlet.
Levine cited research that suggests fertility begins to drop when sperm concentration goes under 40 million per milliliter.
He said that at the rate of current decline, that number is expected to be the global average within a decade.
What is more, we’re looking at averages, and if men are today averaging 50 million sperm per milliliter, there are large numbers of men who today have under 40 million sperm per milliliter — in other words, fertility that is actually suboptimal,” he told the Times of Israel.
Swan, of the New York’s Icahn School of Medicine, said that plummeting sperm counts are part of a wider decline in mens’ health.
“The troubling declines in men’s sperm concentration and total sperm counts at over 1% each year as reported in our paper are consistent with adverse trends in other men’s health outcomes,” she said.
“These include testicular cancer, hormonal disruption and genital birth defects, as well as declines in female reproductive health. This clearly cannot continue unchecked,” Swan added.