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Does Tight Underwear Cause Infertility?

We’ve probably all heard the theory that tight briefs could impact male fertility. This might sound like an old wives’ tale but there could be some truth to it – although we definitely wouldn’t start solely blaming your budgie smugglers for a low sperm count just yet. Here we’ll break down the research and science behind the theory and give our expert advice on the best underwear for male fertility.


Heat Causes Sperm Damage

…and tight underwear can make things a bit hot down there! Let us explain…

Have you ever wondered why the scrotum holds the testicles hanging outside of the body? Well, your core body temperature is usually around 37 degrees and the ideal temperature for sperm production is around 34 degrees. Even though dangling testicles are pretty vulnerable, your body knows that their position is the best place for them to be if they want to make and protect healthy sperm cells from heat damage.

High temperatures can slow down the production of sperm, can damage their DNA and can even kill them completely. Research also indicates that high temperatures can exacerbate oxidative stress, which is another enemy of healthy sperm production.

In a 2015 study, researchers investigated how high testicular temperatures of 40-43°C affect semen parameters and found that increased temperature reduced sperm concentration (from 73M/ml to 42M/ml) and sperm motility (71% to 25%) to about half of the initial values. You can read more about the impact of heat on sperm health here.

There are obviously various ways that your testicles can get too hot – from hot tubs and saunas to a fever illness and even being in a hot country. But what does this have to do with underwear?

Well, as sperm cells like it when your testicles are hanging outside of the body, they aren’t huge fans of you constraining them in tight underwear. Tight underwear not only brings your balls closer to the core of your body but your crotch can get pretty hot and sweaty, especially if you are doing sport or sitting down at a desk all day.


What does the research say?

As always, research into male fertility is sadly lacking, so there aren’t many studies specifically investigating the impact of underwear on sperm health. However, the research that is out there makes for interesting reading!

One 2018 study analysed semen samples from 656 male partners of couples attending a fertility clinic for conception support. They also asked them what kind of underwear they generally wore! The study found that men that primarily wore loose-fitting boxer shorts had a 25% higher sperm concentration than the men that wore other forms of underwear (like tight briefs).

The study also found that the men with lower sperm counts had higher levels of Follicle Stimulating Hormone (FSH). This is probably because the body was boosting FSH levels to try and improve sperm production. You can read more about how FSH and other sex hormones impact fertility here.

In another small study, five men were asked to wear special underwear that forced the testicles up for a duration of 15 hours a day for 120 days. The idea was to increase the average scrotal temperature by about 2 degrees. Researchers found that both motility and sperm count decreased after 3 weeks and only returned to normal over 2 months post-experiment. Whilst this sample size is very small, it does seem to indicate that tight boxers aren’t great for swimmers.

However, there is some research that contradicts these findings. A study investigated the relationship between the type of underwear worn by 501 men and their semen samples. Crucially these were guys right at the start of their fertility journey, rather than those who were already struggling to conceive. In this study, they found no significant differences in sperm health based on underwear choice, and the choice of underwear also showed no correlation to the time it took to conceive.


So should I avoid tight underwear if trying to conceive?

Whilst the scientific jury might still be out on how your underwear can affect the health of your swimmers, keeping your balls cool is definitely important if you are trying to conceive. If you’re a fan of the occasional budgie smuggler, it’s unlikely that they are going to cause infertility, but if you’re happy to swap to a looser fitting boxer, it certainly won’t harm your sperm health – and could potentially be better for them.
The most important thing is to take steps to keep the temperature of your testicles down.

Keep tech away from your testicles
Keep your phone out of your front pocket and use a tray or table when using a laptop. Your tech kicks out more heat than you may realise!

Get moving
If your job involves sitting down for a long time your crotch can get pretty hot so make sure to get up and take your testicles for a walk – it will keep your balls cool and is great for your overall health too.

Say no to saunas
… and hot tubs, and hot baths. The extreme temperatures of saunas and hot tubs are not good for your sperm health.

If concerned, get your sperm tested!
Our at-home sperm test makes it easier than ever to get informed about how your swimmers are doing. The test is performed entirely at home, and you’ll be able to test for important male fertility metrics like concentration, motility and volume – check it out here.

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