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Infertility & Reproduction Health Center

Declining Male Fertility -- Urban Myth Or Alarming Trend?

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Suppressing the development of testicles in utero could lead to infertility 20 years down the road. It also could lead to other problems, such as testicular cancer and hypospadias, a small but correctable malformation of the penis, both of which have been on the rise.

Barzilay says studies have found behavioral and physiological abnormalities in animals exposed in utero to too much estrogen at the wrong time. "But to do studies like that in humans is kind of tough," and even if researchers found the same effect, they may not be able to prove estrogen exposure was the cause.

Lindsay agrees that this argument is plausible, but he isn't convinced that is what is going on. "You can take small bits of hard data and you can try to link them all together into a global idea -- that is where the science begins to break down," he says. "It is very easy to overinterpret some of the harder science -- some of which has given us declining sperm counts, some not. So then coming up with a theory of why there might be declining sperm counts, you might argue, is premature because we haven't even shown that they are."

Lindsay says there are factors that could skew study results, such as the fact that couples are delaying starting a family -- which everyone agrees does affect fertility. There may even be other factors that we may not be aware of -- for example, some of the studies that found declining sperm counts were done in cities.

"People in cities sit down more. That may be a very silly thing, but we know from testicular physiology that testes are meant to be cool, that is why they hang in a little sac outside the body. And we know that if you raise temperature that you can disrupt sperm counts," he says. "Now whether in practice the fact that men wear trousers, they sit down in offices on their testes and keep them warm eight hours a day is enough to cause declining counts, nobody knows."

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