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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

E-cigarettes may be more effective than nicotine patches for pregnant women trying to quit smoking, research found. The study did not raise any new safety concerns with e-cigarettes (vaping).

Pregnant women are advised to quit smoking because of the damage it can cause to developing babies. Many find this difficult. Current guidelines state that nicotine products (such as patches, gum and mouth spray) can help. This research suggests that pregnant women could also consider e-cigarettes.

In the study, similar numbers of pregnant women quit smoking, whether they were given e-cigarettes or nicotine patches. When the researchers looked at women who only used the treatment they were allocated (without using other products), almost twice as many women quit with e-cigarettes than with nicotine patches.

Both approaches were safe. The only meaningful difference was that fewer women in the e-cigarette group had children with low birthweight (weighing less than 2,500 grams). The researchers say this is most likely because e-cigarettes reduced the use of real cigarettes. Low birthweight has been linked with poor health later in life.

E-cigarettes are not currently available on the NHS. However, NHS advice states vaping is much safer for women and their babies than continuing to smoke.

Further advice on quitting smoking in pregnancy is available on the NHS website.

What’s the issue?

Smoking during pregnancy is dangerous for developing babies and can increase the risk of low birthweight, early (premature) birth and miscarriage. There are effective programmes to help women quit smoking.

It is not clear whether nicotine is harmful to developing babies. But the National Institute of Health and Care Excellence (NICE) states that most health problems are caused by toxins other than nicotine in cigarettes. NICE therefore recommends that nicotine replacement therapy (nicotine patches, gum and mouth spray) is considered alongside behavioural support. However, many pregnant women still struggle to quit.

With e-cigarettes, you inhale nicotine in a vapour. E-cigarettes allow people to choose the concentration of nicotine and the flavour of the vapour. The action of vaping is similar to smoking, which means the ritual of smoking continues.

E-cigarettes have been shown to be more effective than nicotine replacement therapy in people who are not pregnant. Increasingly, pregnant women use e-cigarettes to quit smoking. Before this study, it was not known how effective or safe they are during pregnancy.

What’s new?

The study included 1140 pregnant women who were trying to stop smoking. They were recruited from 23 English hospitals and 1 NHS Stop Smoking Service in Scotland. On average, the women were 27 years old, around 16 weeks pregnant and most smoked 10 cigarettes per day.

Half of the women (571) received e-cigarettes; the other half (569) received nicotine patches. All women were encouraged to set a target date for quitting and they were offered support phone calls. However, around 3 in 10 did not set a target date and few women in either group made use of the calls.

At the end of their pregnancy, women reported whether they had quit. Researchers aimed to confirm this by testing the women’s saliva (spit) for traces of cigarette smoke. Only about half (55%) of those who reported quitting provided usable saliva samples.

  • In this group, there was no meaningful (significant) difference in quit rates: 39 of 571 (6.8%) of women in the e-cigarette group and 25 of 569 (4.4%) women in the nicotine patch group quit.

However, some women had quit smoking using a product they were not assigned. For example, 1 in 5 (18%) women assigned patches, regularly used e-cigarettes. In a further analysis, the researchers excluded women who had quit using unallocated products.

  • Only 20 of 564 (3.6%) women in the patch group (who used no other products) quit. That meant women in the e-cigarette group were almost twice (1.9 times) as likely to quit as those using only patches.

E-cigarettes appeared to be more acceptable than nicotine patches. More women regularly used e-cigarettes (77%) compared with nicotine patches (51%). Around 1 in 3 women used e-cigarettes at the end of their pregnancy. In addition, women decreased the concentration of nicotine in their e-cigarettes over the course of their pregnancy.

The researchers looked at safety outcomes, including low birthweight, baby intensive care admissions, miscarriage, stillbirth, and premature birth.

  • The overall safety of the products was similar. However, more women in the patch group had babies with low birthweight (15%) compared with the e-cigarette group (10%).

Why is this important?

This study suggests that e-cigarettes are as safe as nicotine patches for pregnant women. They may also be more effective at helping women to quit.

Only about half of the women returned saliva samples, possibly because it was challenging for women in late pregnancy or with small babies to study instructions, provide samples and post them back. The researchers say that the differences between the groups may have been larger if more women had returned samples.

The results may also have been influenced by media coverage of several young people in the US, who used e-cigarettes and developed a severe lung condition. Ultimately, it was found that e-cigarettes were not to blame, but this news story led to some women stopping e-cigarettes in favour of real cigarettes.

Fewer women in the e-cigarette group had babies with low birthweight. The researchers say a possible explanation is that women in the e-cigarette group smoked less.

Some women used neither e-cigarettes nor nicotine patches. The researchers suggest that women may need more encouragement to make use of these products and of the support phone calls.

What’s next?

The researchers hope this information will help pregnant women and practitioners. The NHS offers pregnant women some forms of nicotine replacement therapy to help them quit, but not e-cigarettes. Stop smoking services recommend e-cigarettes as one of treatment options to smokers who are not pregnant and many provide starter packs. This study may also prompt stop-smoking advisors to recommend e-cigarettes to pregnant smokers.

Further long-term studies are still needed on ex-smokers who do, and do not vape. This could provide information on the safety of e-cigarettes, and whether they help women stay off smoking over the long-term.

In other research, some of the authors found that offering women financial incentives to quit provided value for money. However, interactive text messages did not. Nor did a course of exercise with behavioural support. Future studies could investigate how best to combine e-cigarettes with other support methods.

You may be interested to read

This Alert is based on: Hajek P, and others. Electronic cigarettes versus nicotine patches for smoking cessation in pregnancy: a randomized controlled trial. Nature Medicine 2022;28:958–964.

The value for money of products offered to pregnant women: Jones M, and others. Investigating the cost-effectiveness of three cessation interventions on a national scale using the Economics of Smoking in Pregnancy (ESIP) decision analytical model. Addiction 2022;117:2907–2917.

A Public Health England guide for maternity care providers to help pregnant women quit smoking.

Smoking in Pregnancy Challenge Group information on the use of e-cigarettes during pregnancy.

Funding: The study was funded by the NIHR Health Technology Programme.

Conflicts of Interest: Two study authors have received fees and funding from Pfizer, unrelated to this study.  Full disclosure of all conflicts of interest is available on the original paper.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) at the time of publication. They do not necessarily reflect the views of the NHS, the NIHR or the Department of Health and Social Care.

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