Reduced Fertility from Your Activewear? What the Science Says

We wear them almost daily: leggings, sports bras, running tops. But did you know that your activewear does more than just wick away sweat and allow you to move comfortably? Behind those shiny fabrics and technical coatings lies a hidden world of chemicals. And some of them are linked to… reduced fertility.

Endocrine Disruptors in Your Activewear

Many activewear and yoga clothes are made from synthetic fibers such as polyester, nylon, and viscose. To make the fabric stronger or water-repellent, chemical auxiliaries are added. These include:

• PFAS – the "forever chemicals" that make clothing water and stain repellent
• Phthalates – plasticizers often found in prints and logos
• Bisphenols (BPA/BPS) – building blocks of plastics and coatings
• Triclosan – an antibacterial agent in "anti-odor" activewear

These substances are also known as endocrine-disrupting chemicals (EDCs). They can affect the hormonal system in our bodies.

What the Science Says

Numerous studies show a disturbing link between these substances and fertility.

PFAS – the "forever chemicals"

What it is: PFAS (per- and polyfluoroalkyl substances) are a group of thousands of chemicals that hardly break down in the environment and accumulate in our bodies.^[1]

What they cause: PFAS accumulate in the blood and liver, disrupting hormone balance. Research shows that they affect the production and function of estrogen and progesterone in women – hormones crucial for ovulation, implantation of a fertilized egg, and the course of pregnancy.^[2] In men, PFAS have been shown to lower testosterone levels, which directly impacts sperm production and quality.^[3] Furthermore, PFAS can weaken the immune system and initiate inflammatory processes, indirectly putting further pressure on fertility.

Result: A large study of 1,032 women trying to conceive showed that higher PFAS concentrations in the blood were associated with up to 40% reduced fertility. Specifically, this meant a longer time to conceive, a reduced chance of successful conception per cycle, and possibly a higher risk of miscarriage.^[4] In women undergoing IVF treatments, negative effects were also observed: higher PFAS levels correlated with fewer retrieved eggs and lower pregnancy rates.^[5]

Where do you find it in daily life?

• Non-stick pans (Teflon)
• Water and stain-repellent jackets, rainwear, and shoes
• Food packaging (pizza boxes, popcorn bags, fast-food packaging)
• Cosmetics (waterproof mascara, foundation, lipsticks)
• Carpets and furniture with stain-resistant coatings

Where do you find it in activewear?

• In water-repellent and dirt-resistant coatings (e.g., sports jackets, running pants, and outdoor clothing with a DWR coating).
• Often found in clothing advertised as "waterproof," "stain-resistant," or "easy clean."

Phthalates – silent destroyers of sperm quality

What it is: Phthalates are plasticizers that make plastic flexible. They are known endocrine disruptors that affect sperm quality and sperm motility. They are also associated with disruptions in testosterone balance.^[6]

What they cause: Phthalates bind to receptors in the body that are normally activated by androgens (male sex hormones), thereby disrupting hormone systems. A large-scale systematic review showed that exposure to DEHP and DBP – two commonly used phthalates – provided robust evidence for negative effects on male reproductive health.^[7] Studies show that higher levels of phthalates in urine are associated with lower sperm concentration, less motile sperm, and a higher degree of DNA damage in sperm.^[8] In women, phthalates can impair ovarian function, leading to irregular cycles or reduced egg quality.

Result: Reduced fertility in men due to poorer sperm quality, and in women a lower chance of conception due to hormonal deregulation and reduced egg health. Experiments also showed that DEHP disrupts the testosterone/androgen receptor signaling pathway during spermatogenesis, directly leading to reduced male fertility.^[9]

Where do you find it in daily life?

• PVC floors and wallpaper
• Shower curtains and inflatable products
• Toys (especially soft PVC)
• Cleaning products and air fresheners (as a solvent)
• Cosmetics (nail polish, perfume, hairspray)

Where do you find them in activewear?

• In PVC or plastisol prints (such as logos and large prints on sports shirts or leggings).
• In some coatings of elastic fabrics.
• Especially present in "glossy" or rubbery prints that lie on top of the fabric.

BPA – the plastic that behaves like estrogen

What it is: Bisphenol A (BPA) and variants like BPS are used to make plastic hard and transparent, but also in coatings and dyes. BPA can mimic hormones (especially estrogen) and is linked to poorer IVF outcomes, ovarian dysfunction, and hormonal deregulation in women.^[10]

What it causes: Bisphenol A can act as a weak estrogen in the body. It binds to estrogen receptors, thereby sending incorrect signals to the hormonal system. In women, BPA has been linked to reduced egg maturation, a lower chance of successful IVF treatments, and menstrual cycle disorders. A study of 256 women undergoing IVF found a clear negative association: for every increase in BPA in urine, the number of retrieved eggs decreased by an average of 12% and peak estradiol levels by 213 pg/ml.^[11] In men, BPA reduces sperm production, affects sperm morphology, and increases the risk of oxidative stress in sperm.^[12]

Result: Lower chance of pregnancy, disruption of the natural cycle, and an increased risk of fertility problems in couples trying to conceive. Research showed that elevated BPA levels are associated with an increased chance of implantation failure during IVF treatments.^[13]

Where do you find it in daily life?

• Plastic drinking bottles and food containers (especially polycarbonate)
• Lining of canned goods and beverage cans
• Receipts (thermal paper)
• Dental materials (sealants, composite fillings)
• Household appliances with hard plastic components

Where do you find it in activewear?

• In some synthetic coatings and plastics used in textiles.
• In certain dyes or color-fixing agents.
• Possibly present in activewear accessories such as elastic bands, zippers, or plastic details.

Triclosan – the "anti-odor" chemical that does more than kill bacteria

What it is: Triclosan is an antibacterial agent often added to prevent odor formation. It is known as an endocrine-disrupting chemical linked to lower male fertility and poorer sperm parameters.^[14]

What it causes: Triclosan has antibacterial properties, but also affects thyroid and sex hormones. A systematic review and meta-analysis of 1,312 men showed that triclosan exposure is associated with significant reductions in sperm concentration and motility.^[15] In men, triclosan is linked to lower testosterone levels and poorer sperm quality (less motility and abnormal forms). Animal studies showed that triclosan suppresses testosterone biosynthesis via various molecular mechanisms.^[16] In women, triclosan can disrupt the balance of estrogen and progesterone, affecting the cycle and the implantation of a fertilized egg. Additionally, triclosan can disrupt the gut and vaginal microbiota, which indirectly affects hormonal balance and fertility.

Result: Reduced chance of conception and a disrupted hormonal balance that negatively affects both male and female fertility. A study exposing pregnant rats to triclosan during gestation and lactation found subfertility in male offspring, with increased pre- and post-implantation loss and reduced sperm count and motility.^[17]

Where do you find it in daily life?

• Toothpaste (some brands, now often banned in the EU)
• Mouthwash
• Antibacterial hand soap and shower gel
• Kitchen accessories (cutting boards, sponges) with "antibacterial" claims
• Cosmetics such as deodorants and makeup (still present in older or non-EU products)

Where do you find it in activewear?

• In "anti-odor" or "antibacterial" activewear (e.g., running shirts or yoga tops with odor-fighting claims).
• Sometimes also in socks and compression clothing that is supposed to stay fresh for a long time.

Why activewear poses an extra risk

During exercise, your skin is warmer, moister, and in motion. Precisely the conditions that can accelerate the migration of chemicals from textiles to your skin. A groundbreaking 2024 study showed that microplastics from textiles can release toxic chemicals like flame retardants when they come into contact with sweat, making these substances available for skin absorption.^[18] The study found that up to 8% of the exposed chemicals could be absorbed through the skin over a 24-hour period – and this percentage significantly increased with moister (sweaty) skin.

In addition, synthetic fabrics lose microfibers with every wear or wash. These tiny plastic particles carry chemicals and can be inhaled or ingested. Recent research found microplastics in human reproductive tissue – an area that is now generating considerable scientific interest. A 2024 study detected microplastics in all human testicles examined (23 samples) and dog testicles (47 samples), with concentrations in human tissue three times higher than in the placenta.^[19] In dogs, a higher concentration of PVC in the tissue correlated with a lower sperm count, suggesting that different types of plastic may have different toxicity levels.^[20]

How Certifications Protect You: GOTS and OEKO-TEX 100

Not all activewear is the same. While conventional activewear almost always contains a cocktail of harmful chemicals, certain certifications do offer protection. The two most important are GOTS (Global Organic Textile Standard) and OEKO-TEX Standard 100 – and both work in a fundamentally different way.

GOTS is the strictest certification for organic textiles worldwide. It looks at the entire production process: from the cultivation of organic cotton to the chemicals used during processing. GOTS not only prohibits toxic substances but also sets strict requirements for working conditions, water consumption, and environmental impact.^[21]

OEKO-TEX Standard 100, on the other hand, tests the final product itself. Hundreds of harmful substances are measured in the textile that comes into contact with your skin – regardless of how or where it was made. If there are too many residues of prohibited chemicals, the product does not receive a certificate.^[22]

Our activewear at NOHI NATURAL has both certifications. This means that we meet the strictest requirements both during production and in the final product. Below you can see exactly how GOTS and OEKO-TEX 100 deal with the four endocrine disruptors we discussed earlier:

The main difference: GOTS looks at how the textile is made (chemical inputs and the entire production chain), while OEKO-TEX 100 tests what is ultimately in the final product. Together, they offer the best protection: GOTS ensures that production is clean, and OEKO-TEX 100 verifies that the end result is actually safe for your skin.

What can you do yourself?

Fortunately, you can limit the risks:

• Choose certified natural fibers – Organic cotton with GOTS certification is the safest option. Look for clothing that has both GOTS and OEKO-TEX 100.
• Avoid "water/stain-repellent" claims – these often indicate PFAS, unless explicitly stated to be PFAS-free.
• Be critical of large plastisol prints – these often contain phthalates. Opt for printed designs with water-based inks or embroidery.
• Check quality marks – GOTS and OEKO-TEX 100 apply strict requirements for harmful substances and test hundreds of chemicals.
• Wash smartly – Pre-washing can reduce residues; use a washing bag or filter against microfibers for synthetic clothing.

The Conclusion

The evidence is accumulating: certain substances in activewear can threaten our fertility. While there are still uncertainties about exact dosages, the common thread is clear: the more we expose ourselves to endocrine-disrupting chemicals, the greater the risk.

For those who take their health and future seriously, it is therefore not a luxury to critically examine what you wear. Exercise should support your fertility, not undermine it. That is why at NOHI NATURAL, we choose GOTS-certified organic cotton with OEKO-TEX 100 certification – so you can exercise without having to worry about what's against your skin.