Does polyester underwear cause infertility? Why pants matter

Couple in polyester underwear on bed

Does polyester underwear cause infertility? Why pants matter

I have a very personal reason for writing this article asking whether polyester underwear causes infertility. I have suffered from infertility. So I have a pretty good understanding of what it’s like and how it turns your life and your emotions upside down.

I get how it feels to try not to cry every time you hear a new pregnancy announcement, or the excuses we come up with to avoid any type of social event where people are bringing their children. And social media full of pictures of people’s kids, forget it.

I understand what it’s like to go through endless rounds of IVF, never-ending visits to the clinic, the cost of medication you inject daily into your body. And even trying alternative therapies like acupuncture and completely changing your diet, or doing ANYTHING anyone suggests that might help. 

I have been there. And I was one of the lucky ones: we were eventually blessed with two wonderful daughters. I’d like to think that I appreciate and cherish them in a way that others might not quite understand. 

Me during my IVF fertility journey to get pregnant
Going in for egg retrieval when I was trying to get pregnant
Me and my girls
My happy ending: I consider myself incredibly lucky


So what’s polyester got to do with infertility?

We hear that infertility is rising globally, and various reasons are cited such as women’s empowerment, the rising costs of childcare and lower child mortality. But what if it also has something to do with our clothes?

In the realm of fashion, polyester fabric has long reigned supreme, with its affordability, versatility, and ease of care. Yet beneath the surface of this seemingly innocuous material lies a shocking and largely unspoken truth. The very fabric we wear could be silently wreaking havoc on our reproductive health, affecting semen quality, hormone levels, and even our sexual activity. What?

My journey to have children might be over, but when I found out that polyester could potentially affect your fertility, I was shocked, angry and basically determined to spread the message to help others avoid going through what we did.

Polyester fabric
It seems like the perfect fabric. But maybe it's not. Photo by Landiva Weber on Pexels

The wide-ranging impacts of polyester

Polyester is one of the most commonly used synthetic fabrics, accounting for 54% of all fibres produced. It makes its way into our daily lives in the form of clothing, bedding, and much more. This material, created through a complex industrial process, may look harmless, but it is bad news for the environment due not only to the toxic chemicals used to produce it but also its behemoth microplastic-shedding problem.

Added to this, its implications on our health are far from benign. We looked into this in our article Is Polyester Bad for You? But it gets worse, it seems that our reproductive health is affected too.

Understanding Electrostatic Potentials

You know when you take your clothes out of the tumble dryer and they stick to your skin? Well, that’s electrostatic charge, and it particularly affects polyester. It turns out that high electrostatic potentials in polyester clothing could be contributing to a significant decrease in semen quality and male and female fertility. 

Electrostatic charge in polyester clothing could be affecting our fertility. Photo by CHANNNSY on Pexels

The Impact of polyester on Reproductive Health: Studies

While many people are aware that men should avoid tight-fitting underwear if they and their partner are trying to get pregnant, most are less aware that the type of fabric too plays a serious role. Studies looking into this have shown a distressing correlation between polyester underwear and lower sperm count, decreased erectile funcion and reduced fertility in general.

The late Professor Ahmed Shafik from the Faculty of Medicine at Cairo University is one person that studied this subject intensively. The professor, famous among other things as a pelvic surgeon and personal physician to many dignitaries and world leaders, published around 500 studies and wrote over 1,000 articles in his career. These included several studying whether wearing polyester underwear could cause infertility and reduced sexual function.

Here’s a brief summary: in all studies the participants were divided into polyester and non-polyester underwear-wearing groups. In all cases the polyester underwear-wearing subjects fared worse. 

And for those of you that need more information, here are the most interesting studies (in my opinion) summed up in more detail:

Study One (1992): How wearing polyester underwear can lower your sperm count to zero

The study name says it all: “The contraceptive efficacy of polyester-induced azoospermia in normal men”. Azoospermia means there is no sperm in the ejaculate. This was induced by the 14 men in the study wearing a polyester scrotal sling day and night for 12 months. 

They became azoospermic after approximately 20 weeks and the volume of their testicles fell significantly. Their partners were able to stop taking oral contraceptives and non became pregnant during the study. Approximately 22 weeks after the study finished, sperm count and testicular volume went back to pre-study levels. All five couples that wanted to did eventually conceive.

So, wearing polyester underwear can actually serve as a contraceptive. In these cases it did cause temporary infertility. The study, reported in Science Direct, found that this was due to two factors: an electrostatic field effect and a thermoregulatory effect.

It’s true that most men don’t wear a polyester sling day and night, but many wear their underwear day and night so perhaps it’s not far off.

What I find almost as shocking as the study is that this was carried out in 1992 and I’ve definitely never heard that your partner wearing polyester pants could completely hinder your chances of getting pregnant.

Guy wearing polyester underwear
The study found that wearing polyester could serve as a contraceptive. Photo by Mike Jones on Pexels

Study Two (1993): The effect on sperm of wearing different types of fabric underwear

In this study a group of 31 dogs were used. 12 wore polyester and 12 cotton underwear continuously for 2 years, while 7 control dogs wore nothing. The underwear was deliberately loose-fitting in the scrotal region to avoid the effect of the underwear causing heat. 

After 2 years the underwear was removed and, while the cotton-wearing and control dogs showed no differences, the polyester-wearing dogs showed statistically significant reductions in sperm count, motile sperm, more abnormal forms and the testicles showed degenerative changes.

All effects were reversed 12 months after removing the underwear in 10 of the dogs while 2 continued to be “oligozoospermic” (meaning low sperm count). It was concluded that this was probably caused by the electrostatic potential of the polyester underwear.

Study Three (1992): The effect on the surface of the human scrotum of different fabric types

Here, 21 healthy men were split into three groups wearing either 100% polyester, 100% cotton or a 50:50 polycotton mix underpants for just one hour in the day and one hour at night (repeated four times). 

The cotton wearing subjects showed none and the polyester wearing subjects had the highest electrostatic potentials with the polycotton wearing guys less than half that of the 100% polyester wearers. The effect was higher during the day which was thought to be because of the increased friction and heat caused during the day through movement. 

It is thought that this electrostatic potential causes an electrostatic field across the “scrotal contents” which may lead to the abnormal development of sperm. This suggests that wearing polyester underwear could definitely cause some kind of infertility.

Couple in underwear
Is our underwear making our sperm develop abnormally? Photo by Danny the Designer on Pexels

Study Four (1993): The effect of different types of textiles on sexual activity

As much as unhealthy sperm can negatively affect fertility, outside of the clinic, the painful issue of sexual performance can too. This study looked into just that across a group of 75 rats. 

These were split into 5 groups including one control and four groups wearing 100% cotton, 100% wool, 100% polyester or a 50:50 polycotton mix underwear. Their sexual behaviour was assessed after 6 and 12 months of wearing the garments and 6 months after removing them, plus electrostatic potential was measured. 

All groups (apart from the control) showed a more marked reduction in “intromission to mounting ratio” after 12 rather than 6 months. At 6 months there was no notable difference in the cotton and wool wearing rats. The 100% polyester group showed the highest reduction followed by the polyester-cotton mix. Six months after removing the underwear all groups returned to normal. It was thought that the electrostatic fields generated in the intrapenile structures could explain the reduced sexual activity.

While this study was carried out 30 years ago and has not been repeated by other scientists, and on rats rather than humans, it gives you shocking food for thought.

A study into a group of rats found that polyester inhibited their sexual activity. Photo by Pixabay on Pexels
A study into a group of rats found that polyester inhibited their sexual activity. Photo by Pixabay on Pexels

Study Five (2008): The effect of different types of textiles on conception

After several years, it seems that Professor Shafik turned his attention to the female concern.

In this study, 35 female dogs were split into five groups and wore either pure polyester, pure cotton, pure wool, a 50:50 polyester-cotton mix underwear or no underwear for a year. Eight of the polyester wearing dogs had “diminished serum progesterone in the oestrus of the oestrous cycle” and did not get pregnant during the study either by mating or insemination. However after the study ended they were able to conceive.

It is thought that this is because the polyester causes an electrostatic potential on the skin and this inhibits the ovaries funcioning properly resulting in reduced progesterone.

Study Six (2007): The effect of different types of textiles on pregnancy

This study was less conclusive but in a group of 35 pregnant dogs, split like the study above, all went on to have successful pregnancies apart from two of the seven wearing 100% polyester underwear. They were found to have low serum progesterone levels and had miscarriages in the first month of pregnancy.

This could have been caused by the electrostatic effect of the polyester but the numbers were too small to be conclusive. The good news though is that both went on to have successful pregnancies once the polyester underwear was removed.

These studies are shocking no matter which way you look at them. They all suggest that wearing polyester underwear can cause infertility in some way or other.

But we must remember that they were carried out by one scientist and have not, until now, been replicated by others. They were also carried out on small groups and not on humans in all cases (which I am in no way advocating). We must take them with a pinch of salt and remember that the theories derived are just that, they are theories and not facts.

But I won’t forget them nonetheless.

The dream for many couples. Photo by Ryutaro Tsukata on Pexels.
Polyester fabric could potentially affect women's progesterone levels too. Photo by Ryutaro Tsukata on Pexels.

The Role of Core Body Temperature

It’s not surprising when you think about it that the type of underwear you choose can make a difference. Electrostatic potential aside, cotton underwear and underwear made from natural fabrics tend to breathe better, helping to regulate testicular temperature and fostering higher sperm concentration.

The genital area, for optimal reproductive health, requires a slightly lower temperature than the rest of the body. Polyester, with its heat-retaining properties, can disrupt this delicate balance. 

When opting for natural fabrics, organic cotton and other natural materials like hemp are even better as they’re not treated with any of the nasty chemicals traditional cotton is such as pesticides and insecticides. 

Chemicals associated with polyester and their effects on fertility

Polyester garments and those made from synthetic materials such as polyamide, nylon and acrylic might raise body temperature and even cause electrostatic potential, but they can harbor an array of toxic chemicals too. 

The disturbing effects of flame retardants on fertility

Many synthetic materials, in addition to polyester, contain harmful fire retardants, which have also been linked to fertility problems. One study published in Scientific American suggested a link between flame retardants and reduced human fertility. The study found that women exposed to high levels of flame retardants took substantially longer to get pregnant. 

The study also found that cushions, carpet padding, and other household items contain hormone-disrupting flame retardants called polybrominated diphenyl ethers (PBDEs). These are endocrine disruptors, known to cause adverse health effects.

A further study, published in Springerlink in 2020, show that they can disrupt the balance of sex hormones in the body and cause problems with the reproductive system. 

There are more chemicals in our underwear than we think. Photo by Billie on Unsplash

Other fertility-affecting chemicals used in polyester clothing

Phthalates, another chemical used in polyester production and to make plastics more durable and flexible are known to disrupt reproductive hormones.

According to the European Chemicals Agency, some phthalates can interfere with our hormonal systems and cause allergies. And a further article published in Science Direct linked phthalates to reduced testosterone production meaning lower sperm counts and increased fertility problems in men. 

Meanwhile, Bisphenol A or BPA, commonly known to be found in plastic bottles, is also lurking in lycra or spandex in much of our polyester clothing. Studies have linked this to problems with the female reproductive system too. 

Other chemicals used in the manufacture of clothes such as PFAs, heavy metals, NPEs and VOCs have also all been found to affect our fertilily in some way too. For more on this see our article on the toxic and dangerous chemicals in our clothes.

The list of chemicals in our wardrobe making it harder for us to mate just gets longer.

It’s a mammouth concern, particularly in an era where toxic exposure from industrial chemicals, personal care products, and even water bottles are all around us. These toxins are omnipresent in our daily lives, seeping into our bodies through multiple routes, including skin exposure.

Everyone needs to take notice. Photo by Cody Black on Unsplash

So does polyester underwear cause infertility?

Given all of the evidence, including Shafik’s studies and other research on the toxins associated with polyester, it is hard to deny that wearing polyester underwear doesn’t affect our fertility in one way or another. 

But reproductive health isn’t the only concern. Our hormone balance affects our overall well-being too.

It’s time to acknowledge that our supposedly innocent style of underwear, the choice of fabric, and the presence of synthetic materials in our clothing are not just mundane choices; they can significantly impact our health.

Sustainable and ethical fashion isn’t only about the fashion industry and clothing’s effects on the planet, on animals or on the people who make our clothes, it’s also about its effect on us, the people who wear them!

Group in synthetic underwear and clothing
This affects all of us. Photo by Ardy Arjun on Unsplash

How to give our bodies the best chance to conceive and be healthy

So how do we get around it? Cutting plastics out of our daily lives seems impossible but even cutting synthetic materials out of our wardrobe seems like a Herculean task. After all, they account for 62% of all fibres produced.

We can’t rely on our governments

And while it would be great to rely on our governments to ensure that no chemicals get into our clothes, a report leaked in the Guardian in October 2023 suggests that the EU are reversing their commitment to ban all but the most toxic of chemicals in our consumer products. It just gets more disturbing.

So, we have to take matters into our own hands. Here are some of the best ways to reduce the impact of chemicals in your clothes: 

1. Avoid polyester underwear if trying to conceive

If you or your partner are trying to get pregnant, avoid polyester or synthetic underwear. Look for underwear from natural and organic materials. See our guides on organic cotton knickers or sustainable men’s underwear for example.

2. Look for natural and organic clothes

Seek out natural and organic materials from responsible and transparent brands wherever possible when buying new or second-hand clothes.

3. Check certifications

Look out for the OEKO-TEX, Bluesign, GOTS, EU Ecolabel or Allergy UK certifications (among others) that show a fabric is free from toxic chemicals and safe against your skin.

4. Babies and children need extra care

Take care especially with clothes for babies and children whose skin and not yet fully-developed bodies are particularly susceptible to harmful chemicals.

5. Think about your bed

We spend a huge portion of our lives in bed (especially when we’re trying to conceive!). Consider your mattress and/or mattress topper to find one that doesn’t contain any toxic chemicals.

6. Demand transparency and responsibility

And thinking beyond the way we dress, a call to action is necessary, demanding transparency and responsibility from our governments and the fashion industry about what they’re putting and allowing to be put in our clothes!

Girl protesting
We need to demand change. Photo by Lewis Parsons on Unsplash

Looking ahead

In light of the concerning research and our governments’ inaction, it’s clear that our clothing decisions are more important than we ever thought. Polyester is pervasive in our daily lives and its effects on our fertility and health are now coming to the forefront.

Your choice of clothing can be a powerful tool for positive change, not just for yourself, but for society as a whole. Let’s advocate for transparent and responsible practices in the fashion industry and get the message out there.

We can help ourselves, our friends and loved ones to not only protect our bodies but to procreate too if we so wish!

And if you are suffering from any kind of fertility problem, I wish you luck, love and success in your journey ahead.


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