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Can your Underwear Really Impact your Fertility? 

can tight underwear cause fertility issues?

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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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More to explore

Wearing tight pants and underwear

Studies show that men who wear looser underwear have higher sperm concentration and total sperm count compared to men who wear tighter underwear. So, lose the tight clothes and wear something loose to give your testicles some air.

CONCLUSION: learn more about how heat can affect sperm quality here.


Besides higher mortality rate and various diseases, stress is associated with low sperm quality. Stress is known to be associated with lower testosterone levels and oxidative stress with both playing an essential role in producing and maintaining healthy sperm cells.

CONCLUSION: If you feel stressed, we recommend you get some help so you can have a balanced mental health. For a stress management guide, download the ExSeed app for free and start your personalized action plan today.

Physical activity

Scientific studies show that men who are physically active have better semen parameters than men who are inactive. Fertility specialists also state that regular physical activity has beneficial impact on sperm fertility parameters and such a lifestyle can enhance the fertility status of men.

Prioritizing exercise can help improve your overall health and result in healthy, fast swimming sperm cells that have good chances of fertilizing an egg.

CONCLUSION: Try incorporating exercise in your weekly schedule to you ensure exercising at least twice weekly. We recommend a combination of cardio training and strength exercise. Read more about exercise and male fertility on our blog.


Fast Food
Processed foods damage the health of sperm-producing cells and cause oxidative stress, which lead to poorer sperm quality. Heavy consumption of junk food (every week) can increase the likelihood of infertility since men who consume vast amounts of unhealthy food are at risk of having poor sperm quality. Besides harming your fertility, junk food enlarges your waistline, harms your cardiovascular system, kidneys, and more.

Eating more fruit and vegetables can increase your sperm concentration and motility. It’s important that you consume a healthy diet filled with antioxidants and that you eat vegetables every day. Foods such as apricots and red bell peppers are high in vitamin A, which improves male fertility by nurturing healthier sperm. Men who are deficient in this vitamin tend to have slow and sluggish sperm.

Sugary snacks/beverages: several times a week Excessive consumption of high sugar items can lead to oxidative stress, which negatively impacts testosterone levels and sperm motility. Sugary snacks and beverages are also highly associated with obesity and low fertility.
CONCLUSION: To boost sperm quality, stay away from fast food, processed food, and sugary snacks or beverages. You need to implement a healthy prudent diet filled with necessary superfoods needed for good sperm production. Check out our guide to Male Fertility Superfoods. For personalized guidance and support on how you can start improving your sperm health, check out the Bootcamp.


Direct heat can inhibit optimal sperm production and cause Sperm DNA damage. Sperm cells like environments that are a couple of degrees lower than body temperature. Avoid overheating from warm blankets, seat warmers, heat from your laptop, hot showers, and saunas.

Cigarette smoking

The exposure to tobacco smoke has significant negative effects on semen quality. The damage of cigarettes and nicotine of course depends on how many cigarettes you smoke per day and for how long, but even low usage (up to 10 cigarettes / day) can inhibit healthy sperm production.  

CONCLUSION: Stay as far away from cigarette smoking as possible if you care about your general health and your fertility. Read more here.

Cell phone

When you have your cell phone in your front pocket, your testicles are exposed to electromagnetic radiation, which studies have shown to damage the sperm cells. Put your phone in the back pocket of your pants or in your jacket pocket.


There is a clear association between obesity and reduced sperm quality. At least part of the reason for this is that obese men may have abnormal reproductive hormonal profiles, which can impair sperm production and lead to infertility. 

A BMI higher than 30 can lead to several processes in the body (overheating, increase in oxidative stress in the testes, sperm DNA damage, erectile dysfunction) that can have a negative impact on male fertility. This can result in problems when trying to conceive.  

CONCLUSION: BMI is one of the risk factors that influence semen quality and, for example, sperm motility.  


A beer or glass of wine now and then do not really harm sperm quality. But excess alcohol drinking (more than 20 units per week) can reduce the production of normally formed sperm needed for a successful pregnancy.

CONCLUSION: If you want to stay safe, stay under 14 units of alcohol per week. For more information on how alcohol can affect male fertility, take a look at our blog: “Alcohol and Sperm Quality”.


Studies show that women younger than 35 and men younger than 40 have a better chance of getting pregnant. Men can produce sperm cells almost through their entire life, but the sperm cell DNA is more fragile and prone to damage after the age of 40.

As men age, their testes tend to get smaller and softer resulting in a decline in sperm quality and production. These changes are partly because of an age-related decrease in testosterone level, which plays a very important role in sperm

production. Higher male age (>40 years) is not only associated with a decline in sperm production but also with increased sperm DNA fragmentation and worsened morphology (shape) and motility (movement). These negative effects make the sperm cells less qualified for egg fertilization.

CONCLUSION: with an age under 40, you shouldn’t have to worry much about age as a factor in itself. However, studies have shown a slow decline after the age of 30-35 years

and if you are above 40 years of age, your sperm quality can be affected due to increased sperm DNA damage resulting in a decrease of sperm motility and concentration. Remember that you cannot evaluate the quality of a sperm sample by just looking at it – this requires a sperm analysis.