E-cigarettes help pregnant smokers quit without risks to pregnancy

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A pile of brightly coloured e-cigarettes scattered across a surface

A new analysis of trial data on pregnant smokers has found that the regular use of nicotine replacement products during pregnancy is not associated with adverse pregnancy events or poor pregnancy outcomes.

The PREP 2 study, funded by the National Institute for Health and Care Research (NIHR), used data collected from over 1100 pregnant smokers attending 23 hospitals in England and 1 stop-smoking service in Scotland to compare pregnancy outcomes in women who did or did not use nicotine in the form of e-cigarettes (EC) or nicotine patches regularly during their pregnancy. Researchers took measurements of salivary cotinine levels at baseline and towards the end of pregnancy, and gathered information about each participant’s use of cigarettes or types of nicotine replacement therapy (NRT), respiratory symptoms, and the birth weight and other data of their babies at birth.

The study, led by researchers at Queen Mary University of London, found that e-cigarettes were more commonly used in the group studied than nicotine patches (47% compared with 21%), and also confirmed previous unexpected findings that EC use may reduce respiratory infections in vapers, possibly because the main ingredients of EC, aerosol, propylene glycol, and glycerine, have antibacterial effects.

Women who smoked and also used one of the nicotine replacement products during their pregnancy had babies with the same birth weights as women who only smoked, while babies born to women who did not smoke during pregnancy did not differ in birth weight, whether the women did or did not use nicotine products. Regular use of nicotine products was not associated with any adverse effects in mothers or their babies.

Lead researcher, Professor Peter Hajek from the Wolfson Institute of Population Health, Queen Mary University of London, said: "The trial contributes answers to two important questions, one practical and one concerning our understanding of risks of smoking. E-cigarettes helped pregnant smokers quit without posing any detectable risks to pregnancy compared with stopping smoking without further nicotine use. Using nicotine containing aids to stop smoking in pregnancy thus appears safe. The harms to pregnancy from smoking, in late pregnancy at least, seem to be due to other chemicals in tobacco smoke rather than nicotine."

Professor Michael Ussher of the Institute for Social Marketing and Health at the University of Stirling, who also worked on the study, said:  “This study is important as it shows that individuals who stop smoking early in their pregnancy and switch to vaping or to using nicotine replacement therapy are no more likely to have poor pregnancy and birth outcomes, such as low birth weight, than those who stopped smoking without using these nicotine products. This is good news for pregnant women who are making vital steps to stop smoking.

“This work provides the most reliable evidence as it more carefully measured the levels of use of nicotine products and smoking than previous studies. The problem with any earlier studies reporting harm of vaping in pregnancy is that this could be due to current or previous smoking.”

The study, conducted by researchers at Queen Mary University of London, University of Stirling, University of New South Wales (Australia), University of Nottingham, St George’s University of London, University of Edinburgh, and King’s College London, and St George’s Health NHS Trust, analysed data collected in the Pregnancy Trial of E-cigarettes and Patches (PREP) randomised controlled trial, funded by the National Institute for Health and Care Research (NIHR).

Background information

The published paper

'Safety of e-cigarettes and nicotine patches as stop-smoking aids in pregnancy: Secondary analysis of the Pregnancy Trial of E-cigarettes and Patches (PREP) randomised controlled trial'
Journal: Addiction
Publication date: Wednesday 17 January 2024 
DOI: 10.1111/add.16422
Available at:  https://onlinelibrary.wiley.com/doi/10.1111/add.16422

Funding information 
The study was funded by the National Institute for Health and Care Research (NIHR), ref: 15/57/85.