When we dress our babies, we usually think in terms of cute and convenient. But for that thin, still-developing skin, the fabric itself is a form of “daily exposure” – almost 24 hours a day.
Polyester is everywhere in baby clothes: fleece sleepsuits, cheap pyjamas, leggings, blankets. It’s sold as “practical” and “easy-care”. But what does the science say about polyester and delicate baby skin?
Below is a parent-friendly summary of what real, peer-reviewed research (PubMed articles) suggests – and why many parents are choosing natural fibres like cotton instead.
Quick note: this is educational, not medical advice. If your child has eczema or allergies, always discuss changes with your pediatrician or dermatologist.
1. Baby skin is different – and more vulnerable
Newborn and infant skin is:
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Thinner and more fragile
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Has a higher surface-area-to-body-weight ratio
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Has a still-developing skin barrier and microbiome
That means anything touching the skin – including clothing fibres, dyes and finishing chemicals – can have a bigger impact than in adults.
Children with atopic dermatitis (eczema) are especially sensitive. Multiple reviews on fabrics and eczema note that the type of clothing can worsen itching, irritation and skin barrier damage.PubMed+1
Even though these reviews are not about polyester alone, they consistently flag synthetic fabrics as more irritating than gentle natural fibres.
2. What is polyester, really?
Polyester (usually polyethylene terephthalate, PET) is a plastic made from petroleum. To turn PET into a soft baby onesie, it goes through:
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High-temperature chemical processing
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Spinning into microfibres
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Dyeing
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Finishing with softeners, anti-wrinkle agents, flame retardants or other chemicals (varies by manufacturer)
This combination means polyester isn’t just “a fibre” – it’s a mix of plastic plus residual catalysts, dyes, and finishing agents.
One study that analysed everyday clothing found high levels of antimony (Sb) – a toxic metalloid used as a catalyst – especially in polyester garments (median 141 mg/kg). PubMed The authors also estimated that these elements can migrate from fabric to skin via sweat and friction. While safe limits for babies are still debated, it’s a reminder that polyester isn’t chemically neutral.
3. Polyester, synthetic fabrics and eczema
Several dermatology papers have looked at how fabrics affect people with atopic dermatitis (AD) – many of them children.
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A review in Clinical and Experimental Dermatology notes that synthetic fabrics and wool tend to cause itching and irritate the skin, while cotton has traditionally been recommended as better tolerated.PubMed
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A more recent evidence-based review on textile choice in AD confirms that appropriate fabric selection can reduce symptom severity and flares, and again points to traditional cotton and certain modern smooth fibres as generally safer options.PubMed
Even more concerning, a 2024 study used spatial modelling to link childhood eczema (AD) with environmental exposures. They found that fabrics containing chemicals such as isocyanates (present in polyester, nylon, spandex) could disrupt the normal function of skin bacteria, potentially contributing to eczema. PubMed
Taken together, these papers don’t say “polyester causes eczema” in a simple black-and-white way. But they do suggest:
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Synthetic fabrics are more likely to irritate sensitive skin
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Chemicals used in polyester-type fabrics may disrupt the skin microbiome and worsen eczema in susceptible children
For a baby with already-fragile skin or a family history of AD, that’s a red flag.
4. Chemicals & heavy metals in clothing
The study by Rovira et al. (2015) analysed a wide variety of everyday clothing in direct contact with the skin. Polyester garments stood out with elevated antimony, while some other fabrics (like certain coloured cottons) had high levels of copper. PubMed
Why does this matter for babies?
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Their skin barrier is more permeable
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They sweat more in certain areas (folds, under onesies, back, neck)
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Clothes are worn for very long periods, including sleep
So even if dermal absorption of these elements is relatively low in adults, chronic exposure on baby skin – especially when damp with sweat or urine – is hard to ignore.
Other occupational and case reports show that chemicals associated with polyester production and finishing (for example, triglycidyl isocyanurate in polyester powder paints) can cause allergic eczema and asthma in adults exposed at work. PubMed That doesn’t mean a baby onesie has the same dose, but it shows how certain polyester-related chemicals can sensitize skin and lungs.
5. Microplastic fibres: from baby clothes to baby lungs?
Polyester isn’t just a solid fabric. With wear and washing, it sheds tiny microplastic fibres into the air and dust.
A large review of airborne microplastics notes that synthetic textiles are one of the main sources of these fibres in indoor air, where we and our children spend most of our time. PubMed
Key findings from research on microplastics and fibers:
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Indoor dust studies from homes in 29 countries found widespread microplastics – many of them synthetic fibres originating from textiles. PubMed
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An older but striking study found plastic fibres (including polyester) present in both non-cancerous and cancerous lung tissue from adults, suggesting that these fibres can be inhaled and persist in the lungs. PubMed
More recent toxicology work shows that microplastic fibres, especially from nylon but also polyester, can interfere with developing airway structures in organoid models and animal cells. PubMed
Again, we don’t yet have large long-term studies in babies wearing polyester bodysuits. But we do know:
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Babies spend a lot of time close to textiles (clothes, blankets, soft toys, bedding).
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They breathe closer to the floor, where dust and textile fibres accumulate.
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Their lungs and immune systems are still developing – making them more vulnerable to inhaled pollutants.
That’s enough for many parents (and brands like Cotnly) to take a precautionary approach.
6. Heat, sweat and the “microclimate” under polyester
Even without chemicals or microplastics, the microclimate between fabric and skin matters hugely for babies:
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They can’t regulate their temperature as efficiently as adults.
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Overheating is a known risk factor for heat rash and may be linked to SIDS.
A 2022 study on fabrics for premature baby garments measured thermal and moisture properties of different materials. Cotton knitwear had higher thermal resistance and higher water vapour resistance than certain polyester knits, meaning it retained warmth but also affected how moisture moved.PubMed
In real life, many parents find that polyester baby clothes:
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Feel clammy when the baby sweats
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Trap heat and moisture in skin folds
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Seem to worsen heat rash and irritation
Dermatology reviews on eczema stress that fabrics should allow the skin to “breathe” and not trap sweat, which can worsen itching and inflammation.PubMed+1
7. So… is polyester “toxic” for every baby?
Science is careful, and so should we be:
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There is no single PubMed paper that says: “Polyester baby onesies cause disease X.”
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But there is a growing body of evidence showing:
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Synthetic fabrics are more likely to irritate sensitive skin and worsen eczema
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Polyester garments can contain higher levels of certain elements like antimony
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Textiles are a major source of airborne microplastic fibres, which can be inhaled and have been found in human lungs
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Baby skin and lungs are uniquely vulnerable
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From a holistic, precautionary viewpoint, it’s reasonable to say:
For babies – especially those with sensitive skin, allergies or eczema – minimising direct, constant contact with polyester is a sensible choice.
8. Practical tips for parents: gentler choices for baby skin
If you’d like to reduce polyester on your baby’s skin, here are realistic steps:
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Choose natural fibres for “next-to-skin” layers
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Opt for 100% organic cotton or other natural fibres for bodysuits, leggings, pyjamas and sheets.
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Let synthetic items (like snowsuits) be outer layers, not what touches the skin directly.
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Check labels carefully
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“Soft” doesn’t always mean natural. Look for “100% cotton” rather than “cotton-rich”.
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Avoid “microfibre fleece” or “polyester plush” as sleepwear.
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If your baby has eczema or very dry skin
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Try a 2–4 week “natural fibre trial” – only cotton or other breathable natural fabrics.
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Take before/after photos of affected areas and note itch/scratch behaviour. Bring this to your pediatrician or dermatologist.
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Reduce microplastic dust at home
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Wash synthetic textiles in full loads and line-dry where possible.
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Vacuum and wet-dust regularly, especially in the baby’s sleep and play areas.
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Prioritise quality over quantity
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A small capsule wardrobe of breathable, organic pieces often keeps babies more comfortable than a drawer full of cheap synthetics.
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9. The bottom line
Polyester is convenient, cheap and everywhere – but that doesn’t mean it’s ideal for baby skin.
Real PubMed research shows that:
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Synthetic fabrics can irritate skin and worsen eczema, especially in children. PubMed
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Polyester clothes can contain higher levels of certain elements like antimony and other chemicals. PubMed
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Synthetic textiles are a major source of airborne microplastic fibres, which can be inhaled and have been found in human lung tissue. PubMed
For a developing baby, whose skin and lungs are still finding their balance, gentle natural fabrics are the safer, calmer choice.
