Sperm counts have been declining for years, and new research shows the problem is getting worse
Two key measures of male fertility – sperm count and concentration – have plummeted in recent years, raising concerns about a population increase in men, according to a new study. future.
Between 1973 and 2018, global sperm concentrations more than halved, according to a new analysis by an international team of researchers, published in the journal Human reproduction update magazine on Tuesday. Meanwhile, the total sperm count decreased by 62.3% during the same period.
“Overall, we are seeing a significant worldwide decline in sperm count by more than 50% over the past 46 years, a decline that has accelerated in recent years,” said lead researcher Dr. Researcher and professor at the Hadassah Braun Public School at the Hebrew University of Jerusalem. Health, Hagai Levine, said in a statement.
A 2017 paper, by the same researchers, found that sperm count decline was accelerating in North America, Europe, Australia and New Zealand based on samples collected between 1973 and 2011.
The more recent study, building on previous findings, looked at South America, Asia and Africa to understand the decline in sperm counts around the world. Using samples from more than 57,000 men across 53 countries, combined with statistics used in previous studies, the researchers found that men in those regions also declined. significantly same sperm count as those in the previous study.
The researchers found that sperm density had decreased by 1.16% per year since 1972. However, when the researchers looked at data from after 2000, they found the annual decline was 2.64%.
“Our findings act like a canary in a coal mine,” says Levine. “We are facing a serious problem that, if not mitigated, could threaten the very survival of humanity. We urgently call for global action to promote healthier environments for all species and reduce exposure and behaviors that threaten our reproductive health.”
The analysis did not look at the causes behind the decline in sperm concentration and count, but Levine says that “lifestyle choices and environmental chemicals are adversely affecting fetal development.”
The study was released on the same day as world population 8 billion people, according to United Nations estimates. But all signs point to a slowing overall population growth. It took 12 years for the world’s population to grow from 7 billion to 8 billion, but it is expected to take another 15 years to reach 9 billion.
Meanwhile, the United Nations says fertility has fallen in some countries in recent decades. And “the cumulative effect of lower fertility, if sustained for several decades, could be a more significant reduction in global population growth in the second half of the century,” says the director of the population division. number of the United Nations said in a report. statement.
In the analysis, the researchers note that sperm count is “an imperfect proxy for fertility,” but sperm density and number are closely related to the chances of conception.
“At the population level, the drop means [sperm concentration] from 104 to 49 million/ml that we report here implies a significant increase in the proportion of men with delayed conception,” the researchers wrote in the study. “So, [sperm concentration] provides the most stable and reliable measurement for comparison within and between populations and over time.”
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