During pregnancy, your body becomes more sensitive to everything — heat, pressure, chemicals, allergens. Your skin stretches, your temperature rises, your immune system shifts. And for nine months, clothing is the largest surface area of chemical contact with your body, day and night.
Most pregnancy clothing guides focus on fit and comfort. This one focuses on what the clothing is made of — because the chemicals in textiles matter more during pregnancy than at any other time.
Why Fabric Choice Matters During Pregnancy
Three factors make fabric composition especially important for pregnant women:
1. Increased chemical absorption
During pregnancy, blood volume increases by 40-50%, skin becomes more permeable, and body temperature rises. This means chemicals in contact with your skin — including textile dyes, formaldehyde resins, and finishing agents — are potentially absorbed at higher rates than normal.
2. Endocrine disruption risk
Several chemicals commonly found in clothing are classified as endocrine disruptors — substances that interfere with hormone function. During pregnancy, when hormonal signalling directs foetal development, even low-level exposure to endocrine disruptors raises concerns. Key textile chemicals with endocrine-disrupting properties include:
- PFAS (per- and polyfluoroalkyl substances) — found in stain-resistant and water-repellent clothing. Linked to reduced birth weight, thyroid disruption, and immune effects.
- Phthalates — used as plasticisers in PVC prints and some synthetic fibres. Associated with preterm birth and developmental effects.
- Bisphenols (BPA/BPS) — found in polyester fibres and thermal receipt-style prints on clothing. Known endocrine disruptors.
- Formaldehyde — used in wrinkle-free finishes. Classified as a Group 1 carcinogen. The US has no legal limit on formaldehyde in clothing.
3. Microplastics in placental tissue
A groundbreaking 2020 study published in Environment International detected microplastic particles in human placental tissue for the first time — finding them on both the foetal and maternal sides. A subsequent 2023 study found microplastics in every placenta tested, with polyester and nylon fibres among the most common types identified.
While the health implications are still being studied, the discovery that synthetic textile fibres can reach the placenta adds urgency to the precautionary principle: reduce exposure where you can.
The Safest Fabrics During Pregnancy
Organic cotton — the gold standard
Organic cotton is the safest, most practical choice for pregnancy. It's breathable (critical when your body temperature is elevated), soft against stretching skin, hypoallergenic, and — when certified organic — grown without synthetic pesticides and processed with minimal chemicals. Use for: underwear, bras, t-shirts, sleepwear, leggings.
Untreated linen
Linen is highly breathable, naturally antibacterial, and requires fewer chemical treatments than most fabrics. Its thermoregulating properties help manage the temperature fluctuations common in pregnancy. Linen also gets softer with each wash — increasingly comfortable as pregnancy progresses. Use for: daytime clothing, loose tops, trousers, dresses.
TENCEL / Lyocell
TENCEL (lyocell) is made from wood pulp in a closed-loop process that recovers 99% of solvents. The resulting fibre is exceptionally smooth (reducing friction on sensitive skin), moisture-wicking, and breathable. It's a strong choice for maternity clothing that needs to be soft and comfortable. Use for: underwear, sleepwear, tops, dresses.
Silk
Silk is a natural protein fibre that's hypoallergenic, temperature-regulating, and extremely gentle on skin. Clinical research has shown silk reduces skin irritation in people with eczema and dermatitis. For pregnancy, silk works well for items close to the skin where chemical exposure matters most. Use for: underwear, camisoles, sleepwear.
Merino wool
Merino wool naturally regulates temperature — warming when cold, cooling when warm. Its moisture-wicking properties help manage pregnancy sweating. Merino is also naturally flame-resistant without chemical treatment. Use for: base layers, socks, sweaters, mid-layers in cooler weather.
What to Avoid During Pregnancy
| Avoid | Why | Swap to |
|---|---|---|
| Polyester underwear and bras | Heat-trapping, chemical finishes, microplastic shedding against most sensitive skin | Organic cotton or silk |
| "Wrinkle-free" or "no-iron" garments | Highest formaldehyde levels (300-900 ppm) | Untreated cotton or linen |
| "Stain-resistant" clothing | Likely contains PFAS — linked to reduced birth weight and immune effects | Untreated natural fibres |
| Synthetic sleepwear | 8+ hours of direct skin contact with heat-trapping, chemically treated synthetics | Organic cotton or silk pyjamas |
| New, unwashed clothing | Maximum chemical off-gassing and skin transfer | Wash everything before first wear |
| Ultra-fast-fashion synthetics | Highest chemical loads, lowest quality control, least transparency | Certified natural fibre brands |
Practical Steps for a Safer Maternity Wardrobe
- Prioritise what touches your skin. Start with underwear, bras, and sleepwear — the garments with the most skin contact and the longest wear times. Switch these to organic cotton, silk, or TENCEL first.
- Wash everything before wearing. A single wash removes 60-80% of residual formaldehyde and most water-soluble finishing chemicals. Use fragrance-free, gentle detergent.
- Look for OEKO-TEX Standard 100. This certification specifically tests for harmful chemicals in textiles and has strict limits for baby products — which many brands apply to maternity wear too. See our certifications guide.
- Choose light colours. Dark dyes — especially blues, blacks, and bright colours — contain higher concentrations of potentially sensitising disperse dyes. Light and undyed fabrics carry lower chemical loads.
- Buy secondhand when possible. Pre-owned clothing has already been washed multiple times, dramatically reducing chemical residues. Maternity clothes are often barely worn, making secondhand a practical choice.
- Avoid strongly scented new clothing. A strong chemical smell indicates high levels of formaldehyde and VOC off-gassing. If it smells like chemicals, it is chemicals.
The Bigger Picture
The chemicals in clothing affect everyone, but the stakes are highest during pregnancy when a developing foetus is most vulnerable to endocrine disruption and environmental toxins. The textile industry uses over 15,000 chemicals in manufacturing, most of them unregulated in finished garments.
You can't control every exposure. But clothing — which covers most of your body for most of the day — is one of the largest and most controllable sources of chemical contact. Choosing natural, minimally processed, certified fabrics is one of the simplest precautionary steps available during pregnancy.