Over the past five decades, men’s sperm count worldwide has halved, according to a new concerning study. The findings foretell a looming fertility crisis that first came to our attention in 2017 when researchers revealed significant declines in sperm counts and concentration in men living in North America, Europe, and Australia. The new study found this trend is also true for men in South America, Asia, and Africa, showing this is a global problem — one that will only get worse it seems as the pace of decline continues to accelerate.

Professor Hagai Levine, the study’s lead author from the Hebrew University of Jerusalem’s Hadassah Braun School of Public Health, says that the findings are like a “canary in a coal mine” and, if not mitigated, “could threaten mankind’s survival”.

Levine, along with colleagues from the U.S., Denmark, Brazil, Spain, and Israel, compiled 223 studies with data on sperm samples covering 57,000 men across 53 countries — including regions that had not been reviewed previously — and plotted sperm count in time.

From 1963 to 2018, the results show that sperm counts dropped by 1.2% per year on average. From 2000 to 2018, the rate of decline was a staggering 2.6% per year.

“Overall, we’re seeing a significant worldwide decline in sperm counts of over 50% in the past 46 years, a decline that has accelerated in recent years,” said Levine, who is very concerned about the findings.

Levine said he couldn’t believe the shocking results and had to double-check. What concerns him the most is that this is a global phenomenon with no clear solution or remedy in sight.

“As in climate change, the impact could be different in different places, but generally the phenomenon is global and should be treated as such,” he added. “It looks like a pandemic. It’s everywhere. And some of the causes may stay with us for a very long time”.

Children of Men vibes

Close to 10% of people in the US have experienced fertility problems. About a third of the time, the problem is with the woman, and about a third of the time it’s with the man; the rest of the cases are harder to identify. But while in many couples, fertility test for women is carried out when such problems are encountered, far less attention is paid to male fertility. According to recent studies, we’d be wiser to pay more attention to the male side.

On average, each time a man ejaculates, he typically releases nearly 200 million sperm. It only takes one single sperm to fertilize a woman’s egg and get her pregnant, so it might look like there’s enough sperm to waste. However, in practice conception is a lot more complicated than that.

Even though one sperm is needed for fertilization, there’s a reason why the testicles produce so much sperm: most simply can’t survive the journey to the uterus. For optimal fertility, a healthy concentration of sperm is required of the order of about 40 million sperm per mL.

If this minimum threshold is not crossed, conception is difficult. If follows that as the sperm crisis unfolds, an increasing number of men will likely have to access assisted reproduction. The researchers report a drop in mean sperm count from 104 to 49 million per milliliter of semen, which is dangerously close to a tipping point in global fertility.

This is only an observational study, so the researchers only answered the what, not the why as far as what may cause this phenomenon. But that doesn’t mean that scientists are clueless. Scientists point to risk factors for lowering sperm count, including diet, smoking, obesity, stress, drug and alcohol abuse, as well as exposure to certain environmental chemicals. Concerning the latter, endocrine-disrupting chemicals are the most concerning as these are known to potentially alter levels of testosterone and estrogen.

Somewhat ironically, this news comes on the heels of the U.N. announcement that the global population now numbers over 8 billion people. People who lament we are doomed at the hands of overpopulation might rejoice at the findings of the study. However, there is no real reason for celebration. Low sperm count is not just about making babies — it can serve as a marker for overall male health, so things aren’t looking too good.

“This substantial and persistent decline is now recognized as a significant public health concern. In 2018, a group of leading clinicians and scientists called for governments to acknowledge decreased male fertility as a major public health problem and to recognize the importance of male reproductive health for the survival of the human (and other) species. Research on the causes of this continuing decline and an immediate focused response to prevent further disruption of male reproductive health are needed,” the authors concluded.

The findings were reported in the journal Human Reproduction Update.