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Male fertility is declining. Studies show environmental toxins could be a reason

August 1, 2021 in Blogs

By The Conversation

Ryan P. Smith, University of Virginia

In the U.S., nearly 1 in 8 couples struggles with infertility. Unfortunately, physicians like me who specialize in reproductive medicine are unable to determine the cause of male infertility around 30% to 50% of the time. There is almost nothing more disheartening than telling a couple “I don’t know” or “There’s nothing I can do to help.”

Upon getting this news, couple after couple asks me questions that all follow a similar line of thinking. “What about his work, his cellphone, our laptops, all these plastics? Do you think they could have contributed to this?”

What my patients are really asking me is a big question in male reproductive health: Does environmental toxicity contribute to male infertility?

Infertility is defined as a couple’s inability to get pregnant for one year despite regular intercourse. When this is the case, doctors evaluate both partners to determine why.

For men, the cornerstone of the fertility evaluation is semen analysis, and there are a number of ways to assess sperm. Sperm count – the total number of sperm a man produces – and sperm concentration – number of sperm per milliliter of semen – are common measures, but they aren’t the
best predictors of fertility. A more accurate measure looks at the total motile sperm count, which evaluates the fraction of sperm that are able to swim and move.

A wide range of factors – from
obesity to hormonal imbalances to genetic diseases – can affect fertility. For many men, there are treatments that can help. But starting in the 1990s, researchers noticed a concerning trend. Even when controlling for many of the known risk factors, male fertility appeared to have been declining for decades.

In 1992, a study found a global
50% decline in sperm counts in men over the previous 60 years. Multiple studies over subsequent years confirmed that initial finding, including a 2017 paper showing a 50% to 60% decline in sperm concentration between 1973 and 2011 in men from around the world.

These studies, though important, focused on sperm concentration or total sperm count. So in 2019, a team of researchers decided to focus on the more powerful total motile sperm count. They found that the proportion of men with a normal total motile sperm count
had declined by approximately 10% over the previous 16 years.

The science …read more

Source: ALTERNET

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