Over the past 50 years, human sperm counts appear to have fallen by more than 50% around the globe, according to an updated review of medical literature. If the findings are confirmed and the decline continues, it could have important implications for human reproduction. Researchers say it would also be a harbinger of declining health in men in general, since semen quality can be an important marker of overall health.
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Even if you were to take the same semen sample and run it and do a semen analysis on it in the 1960s and ’70s versus today, you’d get two different answers,” he said. Pastuczak says that in more contemporary studies of semen analysis, ones that rely on samples analyzed by a different method, “you don’t see these trends.” In fact, some studies in Northern European regions show sperm counts going up over time, not down, he said.
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An international team of researchers combed through nearly 3,000 studies that recorded men’s sperm counts and were published between 2014 and 2020, years that had not been included in their previous analysis. The researchers excluded studies that featured only men who were being evaluated for infertility, those that selected only men who had normal sperm counts and those whose study participants were selected based on genital abnormalities or diseases. They included only studies published in English, those with 10 or more men and those with participants whose sperm was collected in the typical way and counted using a device called a hemocytometer.
Overall, the researchers determined that sperm counts fell by sightly more than 1% per year between 1973 and 2018. The study concluded that globally, the average sperm count had fallen 52% by 2018. When the study researchers restricted their analysis to certain years, they found that the decline in sperm counts seemed to be accelerating, from an average of 1.16% per year after 1973 to 2.64% per year after 2020.
“It’s really remarkable that actually the decline is increasing,” said study author Dr. Hagai Levine, an epidemiologist and public health researcher at the Braun School of Public Health and Community Medicine.
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The study authors say they didn’t have enough data from different regions to be able to tell whether some countries had lower average sperm counts than others or whether sperm counts were declining faster in certain areas. Data from 53 countries was included in the review. The authors also didn’t look at what might be causing the decline. “It should be studied,” Levine said.
“While it’s not a cause for panic, because the counts are by and large still normal, on average, there is a risk that they could become abnormal in the future, and we have to recognize that and study that further,” Lundy said.
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Article URL : https://www.cnn.com/2022/11/18/health/sperm-counts-decline-debate/index.html