Vaping in pregnancy carries fewer toxins than smoking, study finds

A new UK study published today in Nicotine & Tobacco Research suggests that exclusive vaping during pregnancy may be significantly less harmful than smoking — at least in terms of exposure to some known toxicants.

The cross-sectional research, led by researchers at City St George’s, University of London, examined 140 pregnant women across five groups, including exclusive smokers, exclusive vapers (all former smokers), dual users of smoking and vaping, dual users of smoking and nicotine-replacement therapy (NRT), and those who never used nicotine or tobacco.

Urine samples were analysed for various biomarkers of exposure including volatile organic compounds (VOCs), tobacco-specific nitrosamines, several cancer-linked heavy metals, and nicotine levels.

Exclusive vapers comparable to never-users

Notably, the study found that exclusive vapers had biomarker levels for most VOCs that were “substantially lower” than those of smokers and dual users — and in many cases similar to those of never-users. This was after controlling for sociodemographic factors and other confounders.

While nicotine levels varied among users, the differences were not statistically significant. However, for most harmful compounds tested — including several VOCs and a polycyclic aromatic hydrocarbon (2-naphthol) — the exclusive vaping group consistently showed much lower toxicant exposure than smokers or dual users.

Despite the relatively promising results for exclusive vapers, the authors caution that this is not a clean bill of health for vaping during pregnancy. The study acknowledges that not all potential toxicants were measured, and exposure to some heavy metals and nitrosamines couldn’t be reliably analysed due to low detection levels.

Furthermore, the researchers stress the need for follow-up studies to examine pregnancy outcomes, birth health, and early life development, which were not addressed in this cross-sectional snapshot.

The findings may reinforce current harm-reduction strategies that support switching to vaping as a cessation tool — even during pregnancy — under medical supervision. For vape retailers, the study provides scientific backing for positioning vaping as a less harmful alternative to smoking.

The study was conducted with support from multiple UK universities and health bodies, and funded by Cancer Research UK.

Recent studies have shown that vapes help pregnant smokers quit without risks to pregnancy and they work better than patches in helping pregnant smokers quit.