Nicotine replacement therapy (NRT) and pregnancy

• pregnant women who smoke should be informed of the risk of smoking to the foetus and themselves and encouraged to stop (e.g. by referral to a smoking cessation service)
  • it is preferable to stop smoking without nicotine replacement therapy (NRT) if pregnant but, if this is not possible, NRT may be recommended to assist a quit attempt, as it is considered less harmful to the foetus than continuing to smoke
    • a retrospective cohort study raised concerns about an increased risk of congenital malformations when using NRT in pregnancy
      • study evaluated the association between congenital malformations of the first child born to 76,768 women in Denmark (1997-2003) and self-reported maternal smoking habits in the first 12 weeks of pregnancy (20,603 smokers; 56,165 non-smokers - 250 used NRT)
        • prevalence of abnormalities for smokers (5.0%) and non-smokers (4.9%) was similar, but the prevalence for NRT users was higher (7.6%): relative prevalence rate ratio vs. other non-smokers 1.61, 95% CI 1.01 to 2.58, NNH 36)
          • however:
            • there was no direct evidence or plausible explanation was provided for the apparent increased risk of NRT when compared with smoking
            • because of the small number (19) of malformations in children of women using NRT relative to other non-smokers (2,719), the study was statistically underpowered to detect the difference, which may have occurred by chance
            • as the study was observational, the results may have been influenced by uncontrolled confounding factors
  • the following advice has been issued with respect to the use of NRT in pregnancy and the findings of the Danish study (3):
    • "Pregnant smokers should always be encouraged first to give up smoking without using NRT. However, these research findings do not mean that pregnant smokers are better off smoking than using NRT. The risks of premature birth or stillbirth caused by smoking are far higher than any potential higher risk of congenital malformation caused by NRT use "
      
      
  • NICE suggest (4):
    
    
    • Nicotine replacement therapy and other pharmacological support
      
      • consider NRT alongside behavioural support to help women stop smoking in pregnancy (see BNF information on NRT)
      • consider NRT at the earliest opportunity in pregnancy and continue to provide it after pregnancy if the woman needs it to prevent a relapse to smoking, including if the pregnancy does not continue (see BNF information on NRT)
      • give pregnant women clear and consistent information about NRT. Explain:
        • that it may help them stop smoking and reduce their cravings
        • how to use NRT correctly, including how to get a high enough dose of nicotine to control cravings, prevent compensatory smoking (nhaling more deeply or smoking more of each cigarette to compensate for smoking fewer cigarettes) and stop successfully
      • advise pregnant women who are using nicotine patches to remove them before going to bed
      • emphasise to pregnant women that:
        • most smoking-related health problems are caused by other components in tobacco smoke, not by the nicotine
        • any risks from using NRT are much lower than those of smoking
        • nicotine levels in NRT are much lower than in tobacco, and the way these products deliver nicotine makes them considerably less addictive than smoking
      • do not offer varenicline or bupropion to pregnant or breastfeeding women
  • a systematic review concluded that (5):
    • NRT used for smoking cessation in pregnancy may increase smoking cessation rates in late pregnancy. However, this evidence is of low certainty, as the effect was not evident when potentially biased, non-placebo-controlled RCTs were excluded from the analysis
    • no evidence that bupropion may be an effective aid for smoking cessation during pregnancy, and there was little evidence evaluating its safety in this population

Notes (4):

• "..NICE's 2010 guideline on stopping smoking in pregnancy and after childbirth (replaced by this guideline) recommended nicotine replacement therapy (NRT) for pregnant women only if they are not able to stop smoking using a behavioural intervention without NRT, and once they have stopped smoking. New evidence showed that NRT may help women stop smoking in pregnancy when added to a behavioural intervention...We found no evidence about the effectiveness or safety of using nicotine-containing e-cigarettes to help women stop smoking in pregnancy. Many of the studies in the effectiveness meta-analysis for nicotine replacement therapies were over 10 years old and most used doses of nicotine that would now be considered to be low.."

Reference:

• (1) MeReC Extra (May 2006);22.
• (2) Morales-Suárez-Varela MM, Bille C, Christensen K, et al. Smoking habits, nicotine use, and congenital malformations. Obstet Gynecol 2006;107:51?7
• (3) Action on Smoking and Health (ASH): Pregnant women using NRT (May 2006)
• (4) NICE (November 2021). Tobacco: preventing uptake, promoting quitting and treating dependence
• (5) Claire R et al. Pharmacological interventions for promoting smoking cessation during pregnancy.Cochrane Systematic Review 2020 https://doi.org/10.1002/14651858.CD010078.pub