Smoking in pregnancy

Despite the increasingly assertive public health messages not to smoke in pregnancy, some women still do. What can practice nurses do to help them stop?

Pregnancy and the postpartum period provide a window of opportunity to promote smoking cessation and smoke-free families.¹

Helping pregnant women who smoke to stop involves sensitive, patient-focused communication, particularly as some may find it difficult to admit that they smoke, because the pressure not to do so during pregnancy is so intense. This makes it all the more difficult to make sure they are offered appropriate support.²

Tact is especially important in relation to disadvantaged pregnant women who smoke, who may smoke because they find themselves in difficult circumstances. The women who are most likely to smoke during pregnancy are those whose circumstances make it most difficult to give it up.²

While midwives have the primary role for identifying women who smoke in pregnancy, it is important that all healthcare professionals with whom the woman has contact provide consistent advice. 2

The key points to get across are:

• Risks to the unborn child
• Dangers of exposure to secondhand smoke (passive smoking) for baby and mother
• Health benefits of stopping (as opposed to cutting down)²

According to a British Market Research Bureau survey, nearly a third of mothers in England smoke in the 12 months before and during pregnancy. Although nearly half gave up before the birth, 30% were smoking again less than a year after the baby was born. One in six women smoked throughout their pregnancy, although many cut down the amount they smoked.³

There is good evidence that women themselves in the UK under-report smoking during pregnancy: in one study, one in four women in the west of Scotland did not admit to smoking at their booking-in visit with a midwife. Routine carbon monoxide (CO) monitoring can improve accurate identification of smokers so they can be referred to smoking cessation services.²

IDENTIFYING SMOKERS

Carbon monoxide testing offers one approach to identifying pregnant women who smoke, but there are conflicting views on the threshold of CO for determining smoking status - some suggest a cut-off point of 3 parts per million, others use a higher measure of 6-10 parts per million. CO quickly disappears from exhaled breath so low levels of smoking, or passive smoking, may go undetected. Nonetheless, it is better to adopt a low threshold to avoid missing a smoker who needs help to stop.

Another approach is to test for cotinine levels in the blood, urine or saliva: cotinine is a metabolite of nicotine and is a useful indication of exposure to tobacco smoke.

BIRTH DEFECTS

Smoking during pregnancy can cause serious health problems including an increased risk of miscarriage, complications during labour, premature birth, stillbirth, low birth-weight and sudden unexpected death in infancy. Smoking during pregnancy increases the risk of infant mortality by an estimated 40%.²

Children whose mothers smoke during pregnancy are more likely to develop respiratory illnesses in childhood, psychological problems such as attention and hyperactivity disorders. Babies born to mothers who smoke are more likely to acquire infections, such as bronchitis and pneumonia, and ear, nose and throat problems, including glue ear.²

A systematic review of observational studies published over half a century between 1959 and 2010 established that maternal smoking was strongly associated with a host of major birth defects, including defects to the heart, musculoskeletal system, gastrointestinal system, cleft palate, club foot and missing or extra digits.⁴

The authors of this study point out that while the - well-documented - risks of miscarriage and low birth weight have some effect on maternal smoking habits, providing information about the risk of birth defects, which have ongoing physical and psychological morbidity (as well as significant healthcare costs) may encourage more women to stop smoking before or early on in pregnancy.⁴

Conversely, if women are made to feel that their smoking habit will lead to censure or harassment by their healthcare professional, it is likely to deter them from admitting that they smoke and therefore being offered the help and support they may need in order to stop.¹

It is therefore worth explaining that it is normal practice to refer all women who smoke to a specialist advisor for help to stop. Use any appointment or meeting as an opportunity to ask women if they smoke, and if they do, explain how NHS Stop Smoking Services can help them to quit. As well as making a referral, give the NHS Pregnancy Smoking Helpline number 0800 1699 169.²

WHAT WORKS?

Interventions which have been demonstrated to be effective in helping pregnant women to stop smoking include

• Cognitive behavioural therapy
• Motivational interviewing
• Structured self-help and support from NHS Stop Smoking Services

Pregnant women are likely to need intensive, ongoing support - brief interventions alone are unlikely to be sufficient.²

Studies have shown that nicotine replacement patch and spray formulations have been shown to double quit rates compared with placebo, and so these are recommended as first line NRT for non-pregnant smokers,5 but there has been comparatively little research into their effectiveness in pregnant women, because of the ethical difficulties of conducting clinical trials in this group.

One small study (in 21 women) found that when nicotine/cotinine concentrations, and maternal and fetal heart rates, were monitored over 8 hours while smoking and again 4 days after using the patch, spray or placebo, NRT reduced both cravings, nicotine and cotinine concentrations. Maternal heart rate decreased with placebo and spray, but not with the patch, and fetal heart rates increased slightly with the active products.⁵

There is evidence that NRT does not increase the risk of stillbirth or fetal growth restriction, and it is being used increasingly (with the backing of national guidelines). However, there is little evidence on whether or not it is associated with congenital abnormalities: it is widely agreed that NRT is safer than smoking, but it is nonetheless advisable to be cautious, especially if there is a chance that the woman is continuing to smoke while taking NRT.⁵

The current recommendation is that NRT should only be offered if attempts to stop smoking without it have failed.

• Only prescribe NRT for use once the woman has stopped smoking
• Only prescribe 2 weeks of NRT
• Only give subsequent prescriptions to women who have demonstrated on re-assessment that they are still not smoking.
• Advise women who are using nicotine patches to remove them before going to bed
• DO NOT prescribe varenicline or bupropion to pregnant (or breastfeeding) women²

CAN WOMEN CHANGE?

Practice nurses - and other healthcare professionals - must sometimes wonder how much difference all their good advice makes to women, especially if the evidence before them suggests that their advice is not followed.

However, one of the few prospective, UK studies looking at women's health behaviours when they were not pregnant and when they were pregnant found that there was encouraging evidence that women complied with some, if not all, of the recommendations aimed at improving their health and protecting their unborn baby.⁶

The Southampton Women's Survey included 1490 women who gave birth between 1998 and 2003. It found a notable reduction in smoking when women became pregnant: before pregnancy, 27% of the women smoked, whereas that figure dropped to 15% in early pregnancy. There were also marked reductions in the amount of alcohol and caffeine consumed. Unfortunately, there was little change in the consumption of fresh fruit and vegetables! Overall, 81% complied with at least three public health recommendations.⁶

CONCLUSION

Despite all the advice that is offered, and the public health messages that are promulgated, some women continue to smoke when they are pregnant. Pre-conception counselling and other contacts with women before and early on in pregnancy offer practice nurses opportunities to provide consistent information to women, to reinforce the benefits to both the unborn baby and the mother's own health that stopping smoking will confer. But equally, it is important that conversations about smoking are approached with sensitivity and tact if women are not to feel harassed. o

REFERENCES

1. DiClemente C, Dolan-Mullen P, Windsor R. The process of pregnancy smoking cessation: implications for interventions. Tobacco Control 2000;9 (Suppl III):iii16-iii21

2. NICE. How to stop smoking in pregnancy and following childbirth. Public health guidance 26, June 2010. Available at: www.nice.org.uk

3. British Market Research Bureau (2007) Infant feeding survey 2005. A survey conducted on behalf of the Information Centre for Health and Social Care and the UK Health Departments. Southport: The Information Centre

4. Hackshaw A, Rodeck C, Boniface S. Maternal smoking in pregnancy and birth defects: a systematic review based on 173,687 malformed cases and 11.⁷ million controls. Human Reproduction Update 2011;17:589-694

5. Oncken C, Campbell W, Chan G et al. Effects of nicotine patch or spray on nicotine and cotinine concentrations in pregnant smokers. J Matern Fetal Neonatal Med 2009;22:751-758

6. Crozier S, Robinson S, Borland S et al, for the SWS Study Group. Do women change their health behaviours in pregnancy? Findings from the Southampton Women's Survey. Paediatr Perinat Epidemiol 2009;23:446-453