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E-cigarettes as effective as patches for pregnant smokers to quit – UK study

E-cigarettes are as safe as nicotine patches for pregnant women and may help more women stop smoking, a UK study in Nature Medicine, involving 1,140 pregnant smokers and funded by the UK National Institute for Health and Care Research (NIHR), has found.

The study, by Queen Mary University of London, is the first to examine the safety and efficacy of e-cigarettes among pregnant smokers. Two stop-smoking medications have been tested with pregnant smokers so far – nicotine replacement treatments such as nicotine chewing gum or patches, and bupropion – an anti-depressant. Nicotine replacement was shown to have only limited effects, while bupropion had none.

The study participants were randomly divided into two groups. One was given e-cigarettes, while the other was given nicotine patches. Quit rates in the two study arms were similar, but some successful quitters in the patch group stopped smoking using e-cigarettes rather than patches. When this was controlled for, the e-cigarette group had better proven quit rates at end of pregnancy than the patch group (6.8% vs 4.4%).

These quit rates are low because they required that women post their saliva samples to confirm no smoking, and very few did that. Looking at self-reported abstinence at end of pregnancy, 19.8% vs 9.7%) were abstinent in the two groups.

Thirty-four percent of the women in the e-cigarette group and 6% in the patch group were using their products at the end of pregnancy. Birth outcomes and adverse effects in women were similar in the two groups, apart from low birth-weight (babies born weighing under 2.5kg), which was less frequent in the e-cigarette group (9.8% vs 14.8%), most likely because women in the e-cigarettes group smoked less.

Study details


Nicotine replacement therapy, in the form of nicotine patches, is commonly offered to pregnant women who smoke to help them to stop smoking, but this approach has limited efficacy in this population. Electronic cigarettes (e-cigarettes) are also used by pregnant women who smoke but their safety and efficacy in pregnancy are unknown. Here, we report the results of a randomised controlled trial in 1,140 participants comparing refillable e-cigarettes with nicotine patches. Pregnant women who smoked were randomised to e-cigarettes (n = 569) or nicotine patches (n = 571). In the unadjusted analysis of the primary outcome, validated prolonged quit rates at the end of pregnancy in the two study arms were not significantly different (6.8% versus 4.4% in the e-cigarette and patch arms, respectively; relative risk (RR) = 1.55, 95%CI: 0.95–2.53, P = 0.08). However, some participants in the nicotine patch group also used e-cigarettes during the study. In a pre-specified sensitivity analysis excluding abstinent participants who used non-allocated products, e-cigarettes were more effective than patches (6.8% versus 3.6%; RR = 1.93, 95%CI: 1.14–3.26, P = 0.02). Safety outcomes included adverse events and maternal and birth outcomes. The safety profile was found to be similar for both study products, however, low birthweight (<2,500 g) was less frequent in the e-cigarette arm (14.8% versus 9.6%; RR = 0.65, 95%CI: 0.47–0.90, P = 0.01). Other adverse events and birth outcomes were similar in the two study arms. E-cigarettes might help women who are pregnant to stop smoking, and their safety for use in pregnancy is similar to that of nicotine patches. ISRCTN62025374.


Recruitment took place between 11 January 2018 and 7 November 2019. Participants were recruited from 23 hospital sites across England and one National Health Service Stop Smoking Service in Scotland. Participants had a median age of 27 years, smoked 10 cigarettes per day, and were on average 15.7 weeks pregnant. The profiles of participants in the two study arms were similar. We were able to establish self-reported smoking status at the end of pregnancy, via direct contact or hospital records, in 531 (93%) and 516 (91%) participants in the e-cigarette and NRT arms, respectively.

Nature Medicine (Open access)

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