Sperm counts have dropped dramatically. Now scientists are trying to find out why
Troubling trend in Western countries should be 'urgent wake-up call,' researcher says.
In what experts are calling a "major public health crisis," a large-scale analysis has found that sperm counts among men in North America, Europe and Australia have experienced a dramatic drop over the past 40 years.
Scientists from Israel's Hebrew University in Jerusalem and the Icahn School of Medicine in New York found a 52 percent decrease in sperm concentration and a 59 percent decline in total count. To arrive at their findings, the scientists analyzed the counts of about 43,000 men who were part of hundreds of studies between 1973 and 2011.
The next step for scientists, as they examine this troubling trend, is why it's happening. Some have suggested smoking, but fewer people are smoking now than 40 years ago, yet the sperm count has only declined. Others have cited obesity, sedentary lifestyles, stress and pesticide use.
But no one's really sure what the true culprit is – which is why there's a vital need for more research.
"Given the importance of sperm counts for male fertility and human health, this study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of the sharp ongoing drop in sperm count, with the goal of prevention," said Dr. Hagai Levine, the study's lead author and a professor at Hebrew University of Jerusalem's Faculty of Medicine.
While many of the men analyzed in the study still fell into the low-but-normal range for sperm count, a greater-than-expected number of them were below the threshold for infertility, which means they may have problems conceiving children in the future, if they haven't already.
"Decreasing sperm count has been of great concern since it was first reported 25 years ago," said Shanna Swan, a co-author of the study and a professor at the Icahn School of Medicine. "This definitive study shows, for the first time, that this decline is strong and continuing."
The study was published this week in the journal Human Reproduction Update.
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