Chemical products designed to straighten or relax hair are generally considered to be safe to use during pregnancy. However, you should avoid products that contain substances called endocrine-disrupting chemicals (EDCs) and products that release formaldehyde when they’re heated. Both are linked to certain health risks (Chan et al 2021, OTIS 2022, Preston et al 2021). Although more research is needed to be sure of the dangers, it may be sensible to limit or avoid them during pregnancy.
What do safety experts say about hair relaxers during pregnancy?
Experts generally consider chemical products that straighten or relax the hair to be safe to use during pregnancy. Many women continue to relax and straighten their hair during pregnancy, with touch-up treatments on hair regrowth every eight weeks or so.
However, recent research has looked more closely at hair-relaxing treatments and products, specifically those marketed at Black women. Researchers say that high levels of EDCs in some products may be a danger to the health of women and their unborn babies (Chan et al 2021, Preston et al 2021).
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EDCs are known as hormone-disrupting chemicals and can affect how your hormones work (James-Todd et al 2021). They have been associated with early puberty, premature birth, fibroids and fertility problems (Preston et al 2021). They are also linked to certain types of cancer (Preston et al 2021), including breast cancer (Coogan et al 2021, Eberle et al 2020, White et al 2021a), ovarian cancer (White et al 2021b) and cancer of the womb (uterine cancer) (Chang et al 2022).
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Studies have shown that these products may contribute to higher rates of premature birth among Black women (Wu et al 2022). They are found in lots of personal care products, but some studies have found that treatments such as hair relaxers, hair oils and leave-in conditioners often contain multiple EDCs (Chan et al 2021, Preston et al 2021). These include lye-based hair relaxers (Coogan et al 2021) and other chemical hair straighteners (Eberle et al 2020, White et al 2021b).
All of this may sound very worrying. However, it’s important to remember that while EDCs have been linked with certain health problems, experts are not absolutely certain about their effects. Most large-scale studies are also from the United States, where hair products often contain chemicals that are prohibited in the UK (WVE 2018).
The Cosmetic, Toiletry and Perfumery Association has reassured consumers that hair straightening products have a long history of safe use in the UK, and are regulated by stringent safety requirements before reaching UK shelves (CTPA 2019).
If you are worried about exposing yourself or your baby to EDCs or other harmful chemicals, it may give you peace of mind to stop using hair-relaxing or straightening treatments during pregnancy, or reduce the amount of treatments you do have.
What about keratin hair treatments?
Unlike hair relaxing, or chemical straightening, keratin hair treatments are not permanent, usually lasting around three months (Aremu and Sherrell 2022, Cobb and Iftikhar 2021). They’re also known as Brazilian Keratin Treatment, BKT or Brazilian Blowout.
The problem with these is that they may contain ingredients that release formaldehyde during the treatment process (Cobb and Iftikhar 2021, Hatsbach de Paula et al 2022), which is a cancer-causing chemical (PHE 2017). If someone is frequently exposed to unsafe levels, it’s been linked to a higher risk of miscarriage (OTIS 2022).
Many countries have placed limits on how much formaldehyde can be used in products. They have also issued regulations about packaging. Following Brexit, the UK government still uses the same safety restrictions as the European Union to keep people safe (GOV UK 2021). This means that products containing formaldehyde (including hair gel, hair-smoothing products and shampoo) are restricted and will eventually be phased out (European Commission 2022).
Although keratin treatments high in formaldehyde are no longer available in the UK (WVE 2018) they may still be found on the web (Cobb and Iftikhar 2021).
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Some manufacturers claim to have formaldehyde-free keratin treatments, but be extra-careful (Cobb and Iftikhar 2021). They may contain chemicals which turn into formaldehyde, such as methylene glycol, or they may contain preservatives that give off formaldehyde during the treatment process (Cobb and Iftikhar 2021, Sherrell 2022).
For complete peace of mind, you may prefer not to have a chemical straightening treatment while you are pregnant. If you do want to have a treatment, always check the ingredients. Avoid those containing ingredients such as methylene glycol, methanediol, methanal and formalin, as they all release formaldehyde when heated (Passam 2022). If you are having the treatment at a salon, always ask whoever is treating your hair to not use these products.
Find out more about the safety of other practices during pregnancy, such as having fake nails, getting your teeth whitened or having a bikini wax.
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