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What Really Reduces Sperm Count? Male Fertility Specialist Weighs In

Photo credit: simone mescolini/Shutterstock

For serious cyclists, perhaps. | Photo credit: simone mescolini/Shutterstock

The topic of infertility is often discussed in the context of women. As a result, men may receive misinformation when it comes to which factors affect fertility. It’s Mountain Dew’s fault! No, spandex! – Do any of these sound familiar? To shed light on the subject, we reached out to Puneet Masson, MD, director of the male fertility program at Penn Medicine. Here, he debunks old wives’ tales and explains when men should ask an expert. 

How is male infertility defined?

We define male infertility as any kind of challenge which results in the inability for a male to achieve a pregnancy through natural means. Let’s take a look at the breakdown. If here are 100 couples trying to conceive, 85 of them will be pregnant at the one-year mark without any intervention. Out of the remaining 15 couples, seven will get pregnant after another six months. Eight couples will be left after a year-and-a-half who are still not pregnant. If you do testing, you will find that the cause of two couple’s infertility can be attributed solely to the male. For four of the other couples, it is purely a female issue, and for the remaining two, it is a combined issue. So, male infertility can affect up to 50 percent of infertile couples, including cases of combined male and female issues.

When it comes to male issues, this could be a problem with sexual functioning, such as trouble with erections, orgasms or ejaculation, or an issue with spermatogenesis, which is the development of sperm. Someone with subfertile semen parameters- which are the standard parameters we test for during a semen analysis- would qualify as a patient with male-factor infertility. The number of hormonal or anatomical reasons for infertility can be vast. Sometimes, even if the biology is working the way it should, it’s not resulting in a pregnancy.

What is the typical testing for male fertility?

The cornerstone of testing for male-factor infertility- and this can be ordered by any physician- is semen analysis. A crucial part of understanding the cause for male infertility is the medical history and exam of the patient. What we want to move away from in medicine, in general, is running a series of tests without talking to the patient or doing an exam.

I’m going to name four things that are typically attributed with decreasing sperm count. Can you confirm or deny?

Spandex/Tight-fitting clothing: It is rare for clothing to be tight enough to cause a male’s testicles to be too snug against their body. Typical brief underwear for example, does not do this.

Mountain Dew: The idea that Mountain Dew can reduce sperm count has been out there for a long time. The truth is, we have no good evidence in human studies – we just don’t know. I tell everyone to eat a heart-healthy diet. Mild to moderate use of anything is okay. Caffeine in moderation is okay. If someone wants to have an occasional Mountain Dew, that’s fine.

Biking: There is some evidence that shows that long-distance cyclists may have a decline in their semen parameters. This could be related to multiple factors. A man’s testicles need to be two to three degrees cooler than the rest of his body to create an ideal environment for sperm to develop. Long distance cyclists often bike 30 miles a day. The testicles are pressed against the body for so long and there is some thought that it could lead to a decrease in parameters. When speaking to the weekend or occasional cyclist, there is no research to prove that biking has this negative effect.

Saunas/Hot tubs: There was an interesting study done with college students. They sat in a hot tub for a controlled amount of time and it was found that 40 percent had a decline in their semen parameters. I tell my patients that while they’re actively trying to achieve pregnancy, avoid any hot tubs or saunas. The scrotal skin is very thin and not nearly as insulated as the rest of our organs which could explain the reaction to extreme temperatures.

Now that we’ve gotten some of the rumored causes out of the way, could you tell us what typically causes male infertility?

One of the most common causes is varicoceles, or large tortuous veins that men have in their scrotum. One in every five men has varicoceles; however, the vast majority of these men have no difficulty conceiving. For some men, although the reason is unclear, varicoceles can have a dramatic effect on their semen parameters. Additionally, some varioceles can be progressive and worsen semen parameters over time.

Hormonal abnormalities – hypogonadism or low testosterone – are another cause of infertility. Testosterone plays an important role in the fertility of sperm as they develop. Many people think that if their testosterone level is low, a quick fix would be to take extra. But, this can shut off the body’s feedback mechanism and stop it from making intratesticular testosterone and therefore mature sperm. Bottom line is: If a hormonal issue is the cause of infertility, it is best to consult an expert.

If a couple suspects they might be dealing with male infertility, what’s the next step?

I see a lot of men who are interested in their future fertility. Someone in their family may have had difficulty getting pregnant or they may have a family history of varicoceles. If there is any concern, make an appointment with me and get tested.

This interview has been condensed and edited for length.

For more information about Penn Fertility Care, click here.