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Professor Felix Naughton, School of Health Sciences, discusses research on the issue of stopping smoking during pregnancy. He explores the efficacy of methods such as NRT, e-cigarettes, and digital support.
What are the effects of smoking during pregnancy?
Smoking tobacco increases the risks of most complications during pregnancy. One of the main ones is that tobacco slows the growth of the foetus, meaning they're more likely to be born under-weight (twice as likely compared to non-smokers), under-developed and premature. It also increases the risk of miscarriage by about one-third and stillbirth by about 50%. These risks increase the more someone smokes during pregnancy. Unfortunately, the damage caused by smoking continues to affect health risks after the baby is born. This includes being associated with a tripling of the risk of suffering sudden infant death, and with increased risks of being asthmatic, experiencing childhood cancer, obesity, having learning difficulties and many other physical and mental health issues.
Do nicotine replacement therapies improve birth outcomes?
The short answer is yes, through helping pregnant people stop smoking, which in turn improves birth outcomes. However, nicotine replacement therapy (NRT) is less effective in helping people who are pregnant stop smoking than those who are not pregnant. There seems to be two reasons for this. The first is that pregnant people metabolise nicotine (and other drugs) faster compared to the speed they would when not pregnant – this appears to peak at around 18–22 weeks gestation. This means they need to use more NRT than an equivalent person who is not pregnant for it to be helpful for stopping smoking.
"Pregnant people attempting to quit typically do not use enough NRT and stop taking it prematurely."
The second reason is that pregnant people often avoid taking medications or take the minimum they perceive as needed. This means pregnant people attempting to quit typically do not use enough NRT and stop taking it prematurely. Our team within the UEA Addiction Research Group worked with colleagues from the University of Nottingham to develop an enhanced form of treatment to help pregnant people use NRT more effectively, which includes enhanced counselling plus support delivered via a leaflet, website and tailored text messages. Currently this treatment, called Baby, Me and NRT, is being evaluated in the SNAP 2 trial in over 1,000 pregnant people.
What about e-cigarettes?
E-cigarettes are a little more complex. Like NRT, e-cigarettes or ‘vapes’ include nicotine, plus they also include propylene glycol, vegetable glycerine and flavours. These extra ingredients, when vaped, release toxicants, although overall at a much lower level than tobacco. This is why vaping is not considered risk free but around 95% less harmful than smoking tobacco. How harmful vaping is for an unborn foetus is challenging to assess, and we don’t know this yet, although most of the chemicals in vapes are not restricted for use in pregnancy.
"The reality is that it’s very difficult to quit for quite a sizeable proportion of pregnant people who smoke, so vapes have a role in supporting smoking cessation among some pregnant people.
The most rigorous studies undertaken don’t show increased risks from vaping in pregnancy compared to using NRT, but more research is needed. More importantly, vaping is an effective stop smoking aid outside of pregnancy. Only one randomised controlled trial among pregnant smokers has tested whether vaping is more effective than NRT for stopping smoking. The results of this trial show vapes are likely to be more effective than NRT, but probably less effective than when used outside of pregnancy. Ideally, no one who is pregnant would continue smoking, but the reality is that it’s very difficult to quit for quite a sizeable proportion of pregnant people who smoke, so vapes have a role in supporting smoking cessation among some pregnant people. Sir Chris Whitty, the Chief Medical Officer for England, summed up the NHS advice on vaping, which I believe also applies for pregnancy: "If you smoke, vaping is much safer; if you don’t smoke, don’t vape."
Is there a difference in the way pregnant people perceive different smoking cessation tools?
Some pregnant people don’t like the idea of using NRT or a vape to stop smoking. When we followed a cohort of pregnant people who smoked through pregnancy and asked them what type of support they most wanted at around 14 weeks gestation, they said one-to-one counselling followed closely by digital support, which includes things like smartphone apps, text messages and websites.
"Some pregnant people who smoke feel like they will be judged by a stop smoking counsellor or simply find this support difficult to access."
Interestingly, by late pregnancy, the popularity of digital support had overtaken one-to-one support. Based on further research, some pregnant people who smoke feel like they will be judged by a stop smoking counsellor or simply find this support difficult to access, resulting in only a minority taking up this help. We have been working on developing digital stop smoking support specifically for pregnant people to address this. Firstly, we developed an automated text message system that provides a tailored stop smoking programme to pregnant people called MiQuit. Based on the findings from two randomised controlled trials, MiQuit helps pregnant people make quit attempts and achieve abstinence from smoking for short periods of time, but not for the whole duration of pregnancy. We are now working on creating a more comprehensive digital support package to make this type of support more effective for pregnancy. This is called eSupport and will include postal delivery of NRT, for those who want it, and a range of support via text message and a smartphone app, including the use of an AI virtual stop smoking counsellor. This six-year project is funded by the National Institute for Health Research and started in June 2024.
Felix Naughton leads a research programme within the UEA Addiction Research Group focused on developing digital health behaviour change interventions, primarily those focused on smoking cessation.
