Western men's sperm counts have plummeted by more than 50 percent over the last 40 years, according to a new study.
According to ABC news, Israeli researchers reviewed hundreds of studies into sperm quality between 1973 and 2011, involving a total of 43,000 men. The findings were published in the Human Reproduction Update Journal.
The study found sperm counts fell an average of 1.6 percent a year for an overall decline of 59.3 percent since 1973. Sperm concentration, a measure of quality, also declined dramatically over the same period, particularly among fertile men. The trend did not improve or worsen in more recent decades, USA Today reported.
"These findings strongly suggest a significant decline in male reproductive health, which has serious implications beyond fertility concerns," the authors concluded, ABC News reported.
Researchers said an increasing proportion of men with sperm counts below the threshold for infertility was "particularly concerning," given that it's "associated with a decreased monthly probability of conception," ABC News reported.
USA Today reported the idea of falling sperm counts has been controversial since it was first suggested 25 years ago. And though Michael Eisenberg, a urologist and assistant professor at Stanford University, said the current data has some flaws, he insists it's enough to justify further investigation.
"As a species, we should be concerned if there's a trend toward declining fertility," Michael Eisenberg, a urologist and assistant professor at Stanford University told USA Today. "There's an urgent need to track this a little more rigorously."
Though the reason for the declining counts isn't know, some factors are suspected, including smoking, a sedentary lifestyle, obesity, stressful life events and so-called endocrine-disrupting chemicals, USA Today reported.
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