We are constantly looking for new ways to improve male fertility in the hopes of giving couples the best chance at successful fertilization and pregnancy. One piece of advice that men have been given for years now is to change their underwear from “tighty-whities” to looser options, but why is this? Does the research still support the advice to shift from briefs to boxers? In this article, we will be delving deep into the science behind underwear choice when trying to conceive and asking, which underwear is the best for sperm count?
Key takeaways
- There is evidence that underwear choice can impact sperm health if you are struggling with fertility issues.
- 100% cotton boxers are the best choice of underwear for sperm count.
- Sleeping naked may help increase fertility.
- Synthetic fabrics such as polyester may negatively impact fertility.
Boxers vs briefs — which is better for sperm count?
The age-old debate of boxers vs briefs came crashing into the world of male-factor fertility back in 2018 when a study published in the journal Human Reproduction concluded that men’s choice of underwear could affect their testicular function. The study involved 656 male subjects and examined semen quality parameters compared to underwear choice. The study concluded that men who reported they wore boxers more often showed elevated sperm concentration and overall count compared to those in the study wearing other styles of underwear. The semen gathered from the boxer-wearing participants contained as much as 25% higher sperm concentrations than the other participants, as well as higher percentages of motile sperm and sperm counts.
All of these factors can significantly impact fertility as they influence the ability of the sperm to reach and successfully fertilize the egg.
More recent studies have replicated these findings. A 2020 study into the effect of modifiable lifestyle factors on semen quality found that wearing tight underwear was related to lower motility.
Wearing tight-fitting underwear is now considered to be one of many lifestyle choices that can negatively impact male fertility due to genital heat stress. The testis is a temperature-sensitive organ, and to ensure the production of normal sperm, the scrotal temperature needs to be maintained at 2–7 degrees Celsius below core body temperature. If the scrotal temperature rises above this, it can cause genital heat stress, leading to impaired spermatogenesis, lower sperm counts, poor sperm motility, and abnormal sperm morphology in the ejaculate.
The studies looking at underwear choice have some limitations worth noting. These samples were all taken from men seeking fertility treatment, so these results may not accurately reflect the effects of underwear choice on normally fertile men. One study published in The Lancet examined underwear choice on the time it took for 501 couples to fall pregnant. These were participants who had not been identified as having fertility issues. The results showed no significant difference in semen health or any impact of underwear choice on time-to-pregnancy.
So what does all this mean for those deciding on steps to take to improve their fertility? Tighter underwear could affect male fertility but it’s unlikely to make a significant difference in otherwise fertile individuals. However, as it is an easy, low-cost lifestyle change to make and maintain, it might still be worth considering switching from tighter underwear to boxers if you are thinking of trying for a baby. Alternatively, you could arrange for semen analysis to learn more about your sperm health. For more information on how to arrange this, click here.
Going beyond boxers vs briefs
What other factors around underwear choice can affect male fertility?
The debate on underwear choice and fertility isn’t purely limited to the two options of boxers or briefs these days. Now, there are other factors and options to consider.
Should you sleep naked to improve your fertility?
One study examined the effect of underwear choice at bedtime on men’s semen quality. 473 participants had their semen analyzed, and although researchers found no significant impact in terms of conception delay, there were some differences in semen parameters noted, depending on the choice of underwear at bedtime. These positive changes in semen health measures were most notable in men who changed their nighttime underwear to a cooler option.
What about “testicle hammock” underwear?
There are many “testicle hammock” underwear options available online now but do they really support fertility as many of them claim to? A lot of the websites refer to the original 2018 study linked above, citing lowered testicular temperature as a desirable product feature. According to one online store, this “pouching of the testicles” protects against rising testicular heat being “the silent killer of fertility”. There is, at present, no firm evidence linking the use of testicle hammocks to improved fertility. In fact, these underwear types are quite a tight fit, so they could have a similar impact on sperm as wearing briefs. Research is needed to test out the claims made by these underwear firms.
Synthetic underwear may be detrimental to fertility
There is some evidence to suggest that fertility may be impacted by choice of underwear in terms of fabric choice rather than tightness. One study looked at textile fabric and spermatogenesis in dogs and found that cotton fabrics did not affect fertility compared to polyester underwear, which was shown to cause a significant decrease in sperm counts. The researchers concluded that the electrostatic charge generated by the polyester material may have been responsible for the significant decline.
Polyester, which is a commonly used synthetic material for underwear, has been shown to hold in heat and is less breathable than other materials. This may raise the testicular temperature, leading to scrotal heat stress.
A follow-up study looking at sexual behaviors of men wearing different fabric underwear for periods of 6 and 12 months showed a deleterious effect on sexual activity in men wearing polyester underpants compared to cotton and wool textiles.
These studies were very small, so more research is needed to examine the link between textile choice for underwear and fertility.
What about the environmental chemicals found in synthetic underwear?
Studies have now found a link between environmental chemicals sometimes present in synthetic underwear and a significant negative impact on fertility. The genital area is one of the most sensitive parts of the human body and is highly susceptible to chemical absorption. According to chemists from the University of California, the scrotum is approximately 20 times more permeable to chemicals compared to other areas of our skin. Some common chemicals your scrotum may be exposed to when using conventional fabric include:
- bleaches
- softeners
- heavy metals
- harsh petroleum scours
- flame retardants
- formaldehyde
- ammonia
- chemical dyes
Exposure to these types of endocrine-disrupting chemicals can cause significant difficulties in both male and female fertility.
Can “cooling underwear” actually improve fertility?
Given what we know about the effect of scrotal temperature on male fertility, companies have taken the idea of “fertility-supporting underwear” to the next level and produced “cooling underwear”. This is based on research showing that wearing specially designed cooling devices can significantly decrease scrotal skin temperature and, therefore, could positively impact semen health parameters in individuals struggling with male-factor fertility.
One study found that significant increases in sperm motility and vitality were demonstrated after cooling but that the devices were uncomfortable, impeded work, and lost cooling rapidly. Therefore, at this stage, there is a call for more work to improve the wearability of cooling devices for use as a therapeutic tool for enhancing sperm parameters and reducing infertility.
How to choose the best underwear while trying to conceive
When looking for underwear that best supports your fertility while trying to conceive, it is worth choosing underwear that is:
- loose fitting
- made from breathable fabric
- made from natural materials such as 100% cotton
It is also advisable to consider sleeping naked or, at the very least, changing from tighter underwear options to looser underwear to allow breathability and cooler scrotal temperatures while you sleep.If you have any concerns about your fertility and would like help while trying to conceive, you might want to consider having a semen analysis. Legacy can support you every step of the way through this stage of your fertility journey. Click here for more information.