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Scientists issue vape warning to women over hidden chemical's pregnancy risk

Scientists issue vape warning to women over hidden chemical's pregnancy risk

Scientists have raised concerns about vanillin, a common vape flavouring, after a lab study found it could affect cells involved in early development.

woman with head obscured by smoke from a vape

MadeForMums

Published: August 13, 2026 at 10:25 AM

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Scientists have raised concerns about a chemical commonly found in flavoured vapes after new research suggested it could interfere with cells involved in the earliest stages of human development.

Researchers at the University of California, Riverside (UCR) investigated vanillin, the chemical responsible for vanilla's characteristic smell and taste, and found that exposure affected human embryonic stem cells in laboratory tests.

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It's a concerning finding for anyone who vapes while pregnant or trying for a baby, but there's an important caveat. The research was carried out on cells in a laboratory, not pregnant women or developing babies, and experts say it does not prove that vaping causes miscarriage or fertility problems.

What did scientists find in the vape study?

Embryonic stem cells have the ability to develop into the different types of cells needed to form the body. Researchers exposed these cells to vanillin at concentrations they said were “relevant to maternal e-cigarette exposure”.

According to the research, lower doses stopped some normal developmental processes from taking place, while higher concentrations killed cells altogether.

Professor Prue Talbot, lead author of the research at UCR, explained that the team focused on vanillin because it is frequently used in e-cigarette liquids, often at high concentrations, and because embryonic cells have a channel called TRPV4 that was likely to bind with it.

These changes are potentially very serious and could prevent normal development of embryos,

Professor Prue Talbot, lead author at the University of California, Riverside

The researchers said some of the affected stem cells would normally go on to form the nervous system and tissues including muscles.

Does this mean vaping can cause miscarriage?

No. The study does not establish a link between vaping and miscarriage, difficulty conceiving or other pregnancy complications in humans.

The experiments involved embryonic stem cells in a laboratory, rather than pregnant women or embryos developing during pregnancy, and independent scientists have urged caution when interpreting the findings.

Professor Benedikt Berninger, professor of developmental neurobiology at King's College London, who was not involved in the study, described the evidence as “still very speculative, as it is based on a very simplified in vitro model and also a limited set of data”.

He added: “It is well possible that in a real embryo, since it is more complex, the behaviour of the cells is under a more robust control and hence they would not be so easily misdirected.”

Professor Berninger called for further research to “make sure that the conclusions and resulting warnings are indeed warranted”.

What our MadeForMums GP says about vaping in pregnancy

The new findings add to a bigger question for parents-to-be: just how much do we actually know about the safety of vaping during pregnancy?

MadeForMums expert GP Dr Philippa Kaye, who has a particular interest in women's and children's health, says there are still significant gaps in the evidence. While e-cigarettes are considered less risky than smoking during pregnancy, that doesn't make vaping risk-free.

We don't truly know if it is safe to vape when you are pregnant or not – because so little specific research has been done. It's true to say that using e-cigs is currently considered less risky than smoking during pregnancy but that doesn't mean they're safe.

Dr Philippa Kaye, MadeForMums expert GP

Dr Kaye explains that e-cigarette vapour contains potentially harmful chemicals, although at lower levels than cigarettes, and it isn't yet clear whether those chemicals can harm an unborn baby.

For pregnant women who currently smoke, however, the distinction matters. Dr Kaye says vaping is safer than continuing to smoke, although doing neither is the safest option.

If you need help giving up smoking during pregnancy, she says a doctor or midwife will generally recommend nicotine replacement therapy (NRT), such as patches or gum, rather than e-cigarettes, because more is known about its safety and risks.

However, Dr Kaye adds: “But if e-cigarettes help you quit smoking more effectively than NRT, it's better to vape than continue to smoke.”

What exactly is vanillin?

Vanillin isn't exclusive to vaping products. Dr Winston Morgan, reader in toxicology and clinical biochemistry at the University of East London, explains that it is the main compound responsible for vanilla's familiar smell and taste.

It occurs naturally in vanilla beans and is also manufactured for use in foods, fragrances, and flavourings.

Dr Winston Morgan, reader in toxicology and clinical biochemistry at the University of East London

The new research specifically looked at exposure of embryonic stem cells to vanillin in the context of concentrations considered relevant to e-cigarette exposure. It does not suggest that eating vanilla or vanilla-flavoured foods carries the same potential risk.

So should you avoid vaping if you're pregnant or trying for a baby?

Professor Oliver Jones, professor of chemistry at the Royal Melbourne Institute of Technology University, said the study was at an early stage and had not established that vanillin in vapes causes harm during a human pregnancy.

He said: “This is not the first time that vanillin in vapes has been implicated in development issues, although previous work was done in frogs.”

The work does not prove a link between vaping and women having difficulty conceiving and/or miscarriages. However, given the potential consequences, I think avoiding vapes and vaping while pregnant or trying to become pregnant is sensible general advice.

Professor Oliver Jones, professor of chemistry at the Royal Melbourne Institute of Technology University

The NHS advises that vaping is “much less risky than smoking”, while the researchers behind the latest study are calling for regulators to consider mandatory ingredient disclosure on vape packaging.

If you're pregnant, trying to conceive and concerned about vaping, or need help to stop smoking, speak to your midwife, GP or local stop-smoking service for support.

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