It might sound surprising, but what you wear can actually influence your reproductive health — especially when trying to conceive or preparing for IVF.

From tight underwear and synthetic fibres to overheating the testicles or ovaries, subtle environmental and physical factors can affect hormone balance, sperm health, and even egg quality. This post explores what the research says — and how a few small clothing swaps could support your fertility journey.

The Role of Body Temperature in Reproductive Health

When it comes to fertility, temperature matters — and not just during ovulation tracking. Both the ovaries and testicles are sensitive to heat.

• Sperm production occurs best at slightly below body temperature, which is why testicles hang outside the body

• Ovarian follicles and hormone signalling can be influenced by inflammation or heat stress

• IVF patients are often advised to avoid saunas, hot tubs, or overheating during stimulation

Clothing plays a part in this — especially fabrics that trap heat or restrict airflow.

Tight Clothing and Male Fertility

Let’s start with one of the most well-documented areas: tight underwear and sperm health.

What the Research Shows:

• Tight-fitting briefs or synthetic gymwear can increase scrotal temperature

• Higher testicular temperature is linked to lower sperm count and motility

• A 2018 Harvard study found that men who wore loose boxers had 25% higher sperm concentrations than those who wore tight underwear

• Compression shorts and cycling gear may also reduce airflow and raise temperatures

What You Can Do:

• Switch to loose-fitting, breathable cotton boxers

• Avoid tight jeans or gymwear for extended periods

• Sleep without underwear or opt for loose pyjama bottoms

• Choose natural fibres that allow heat to dissipate

What About Women’s Clothing?

The link between female fertility and clothing isn’t as direct — but there are still ways your wardrobe could influence your cycle.

Heat and IVF:

During IVF stims, your ovaries are working overtime, and your body is more sensitive to temperature.

• Overheating (from tight shapewear, synthetic leggings, or layers) can contribute to bloating and inflammation

• High temperatures around the abdominal area may increase core body heat, which some research suggests could impact egg quality in animals

• Wearing cool, breathable fabrics may support comfort, circulation, and hormonal regulation

Vaginal Health & Fertility:

Tight synthetic clothing can also affect vaginal flora and pH balance, which may lead to yeast infections or bacterial imbalance — indirectly affecting fertility if inflammation is present.

Best Fabrics to Wear When TTC or During IVF

Choosing clothes that support circulation and temperature regulation doesn’t mean giving up your style — just being intentional.

Better Choices:

• Organic cotton

• Linen

• Bamboo or modal

• Wool blends (for warmth without overheating)

These materials are breathable, gentle on skin, and allow airflow — all helpful when navigating the hormonal rollercoaster of treatment.

What to Avoid (or Wear Less Often)

• Shapewear or tight high-waisted control pants during stims

• Non-breathable leggings for long days (especially polyester or nylon)

• Synthetic underwear that traps heat and moisture

• Thermal wear or heavy layering without breathability

Remember — occasional use won’t derail your cycle, but consistent choices can make your body feel better supported.

Clothing and Emotional Wellbeing

There’s also the emotional side: IVF often makes people feel out of control or disconnected from their bodies. Wearing comfortable, breathable, and non-restrictive clothes can support a sense of calm, softness, and self-trust.

Consider:

• Loose dresses or flowy skirts during bloated days

• Pyjamas that let your belly breathe post-injection

• A favourite soft jumper during recovery days

• Undergarments that feel like support, not restriction

It’s Not About Perfection — Just Support

Will one pair of tight jeans ruin your chances of success? No. But your clothes can affect things like temperature regulation, hormone comfort, vaginal health, and sperm quality.

Making small, mindful changes to what you wear — especially during IVF stimulation or egg development windows — can help your body stay cool, calm, and ready.

Just like food and supplements, your clothing choices can be another layer of gentle fertility support.