Paris (AFP) – Sperm counts among men worldwide are declining at an accelerating rate after halving in the past 40 years, a major new study said Tuesday, calling for action to halt the decline.
The study, led by Israeli epidemiologist Hagai Levine, updates a 2017 survey that only controlled for North America, Europe, Australia and New Zealand. The new study includes data from more than 57,000 men collected in more than 223 studies in 53 countries, making it the largest meta-analysis ever conducted on the topic. With the new countries added, it confirmed the 2017 finding that sperm counts have halved over the past four decades. Between 1973 and 2018, the sperm count in men not known to be infertile dropped by more than 51 percent, from 101.2 million to 49 million sperm per milliliter of sperm, the new study found. “Furthermore, the data suggest that this global decline continues into the 21st century at an accelerating rate,” says the study published in the journal Human Reproduction Update. Sperm count declines at a rate of about 1.1 percent per year, according to research. More action and research is urgently needed “to prevent further disruption of male reproductive health”, he added.
“We honestly don’t know why”
Sperm count isn’t the only factor affecting fertility—the speed of sperm movement, which wasn’t measured in the study, also plays a role. And the lowest sperm concentration of 49 million is still well above the range considered “normal” by the World Health Organization — between 15 and 200 million sperm per milliliter. Sarah Martins da Silva, a reproductive medicine specialist at the University of Dundee in Scotland who was not involved in the study, said it showed that the rate of decline in sperm count has doubled since 2000. “And we really don’t know why,” he added. “Exposure to pollution, plastics, smoking, drugs and prescription drugs, as well as lifestyle, such as obesity and poor diet, have been suggested as contributing factors although the effects are poorly understood and unclear.” Other experts said the new study did not resolve their skepticism about the 2017 research. “I remain concerned about the quality of the data in the published papers, particularly in the more recent past,” on which the analysis is based, Alan Pacey of the University of Sheffield, UK, told AFP. While he welcomed the “very elegant meta-analysis,” Pacey said he believed “we’ve just gotten better” at the difficult task of counting sperm, which could account for the drop in rates. But Martins da Silva dismissed critics of the study’s results, saying “the numbers and consistent findings are hard to ignore.” © 2022 AFP
