TOBACCO AND NRT USE IN PREGNANCY

Tobacco smoking during pregnancy is associated with a higher risk of adverse pregnancy, fetal and longer-term adverse outcomes in the offspring including spontaneous abortion, stillbirth, premature delivery, intrauterine growth restriction, placental abruption, congenital malformation, sudden infant death syndrome, childhood behavioural/neurodevelopmental disorders, asthma, obesity, diabetes and cancer. As such, smoking cessation is strongly encouraged during pregnancy and for women considering pregnancy.

In the non-pregnant population the most effective smoking cessation strategy involves a combination of behavioural support therapy with pharmacological smoking cessation aids. In the UK, licensed NRT products include traditional preparations such as gums, sublingual tablets, inhalators, lozenges, oromucosal/nasal sprays and transdermal patches, and, more recently, electronic nicotine delivery systems (ENDS) or e-cigarettes.

Efficacy data concerning pharmacological smoking cessation aid use in pregnancy are both limited and conflicting. While some studies of traditional NRT use in pregnancy have demonstrated efficacy others have not, and a 2015 Cochrane review demonstrated no statistically significant improvement in smoking cessation with gestational NRT use in comparison with placebo. It is possible that NRT offers benefit over placebo in certain women but not in others. There is also some evidence that certain outcomes amongst smokers who attempt cessation with NRT are improved in comparison to those women who do not use NRT.

Traditional NRT – Published human pregnancy NRT exposure data do not provide evidence of increased risks of spontaneous abortion, intrauterine death, neonatal complications or neurodevelopmental impairment. There is currently no robust evidence that NRT use in pregnancy increases the overall risk of congenital anomaly or major malformation, although one study has identified a statistically significant increased risk of respiratory system defects specifically. As only a small number of studies have assessed the risk of specific defects and no additional studies have investigated respiratory system defects, further studies are required to establish the validity of this association.

Increased rates of preterm delivery and low birth weight have been described in studies which compared pregnancies in women using NRT with pregnancies in non-smokers. However, these results are likely to have been influenced by maternal relapse and concomitant tobacco use among the NRT users. Furthermore, studies of fetal growth and gestational length which compared pregnancies in women attempting smoking cessation with NRT against those attempting cessation without NRT, or continuing to smoke tobacco, have not identified any adverse effects of gestational NRT on these outcomes.

ENDS/e-cigarettes – No studies investigating either the efficacy or safety of ENDS/e-cigarettes in pregnancy have been located in the published literature.

As traditional NRT is the most widely studied gestational smoking cessation aid with respect to both efficacy and safety, where intervention is considered necessary following an individual case assessment, use of traditional NRT in combination with behavioural support is currently recommended by NICE as the first choice method of aiding smoking cessation in pregnancy. No studies have compared the efficacy of different traditional NRT formulations, but the limited studies comparing NRT formulation safety have not identified any notable variation in the risk of adverse effects. Expert recommendations have suggested that, as transdermal patches may provide a higher cumulative dose of nicotine which is constantly supplied to the fetus, use of 24-hour transdermal patches may be less appropriate than other immediate release forms of NRT in pregnancy. Where transdermal patches are required, pregnant women should be encouraged to discard these during sleep to limit transplacental nicotine transfer to the fetus.

Exposure to NRT at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors which independently increase the risk of adverse pregnancy outcome, or for which enhanced follow-up is required, may be present in individual women. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.

Given the limited information available concerning the efficacy or safety of gestational ENDS/e-cigarette use, use of these devices as a smoking cessation option cannot currently be recommended in pregnancy.