CLINICAL Management of smoking in pregnant women Colin Mendelsohn Gillian S Gould Cheryl Oncken Background In this article we review the natural history of Smoking is the most important preventable cause of adverse outcomes in smoking during pregnancy and postpartum. The pregnancy. However, most smokers who become pregnant continue to smoke and growing list of health effects on the mother and most of those who quit relapse after delivery. child are outlined. Finally, we suggest updated evidence-based strategies for use by health Objective professionals during pregnancy and lactation. This article explores the relationship between smoking and pregnancy, and reviews the evidence for best practice intervention by general practitioners. Natural history of smoking, Discussion quitting and relapse in Continuing to smoke during pregnancy is strongly associated with socioeconomic pregnancy disadvantage, mental illness and Aboriginal and Torres Strait Islander populations. Pregnant smokers fall into three groups, which Quitting is more difficult for these groups and interventions assist only sixin every 100 pregnant smokers to quit. Behavioural counselling is the first-line treatment. require different approaches: Nicotine replacement therapy (NRT) can be offered if the smoker is unable to quit • Those who quit spontaneously when finding without it, although its efficacy is uncertain. Adequate doses of nicotine and good out they are pregnant. This group should be adherance may be required for the best results. The use of NRT in pregnancy is encouraged to maintain abstinence. likely to be less harmful than continuing to smoke. Women should be encouraged • Those who continue to smoke and require to quit smoking before becoming pregnant. assistance to quit. Keywords • Those who quit but relapse postpartum and may substance-related disorder; obstetrics/pregnancy; Indigenous health services; benefit from further counselling. women’s health Spontaneous quitters Up to 45% of women who smoke before pregnancy stop before their first antenatal visit.8–10 Women who quit spontaneously are more likely to have Smoking in pregnancy is the most higher social status, no smoking partner, a lower important preventable cause of a wide degree of nicotine dependence, low parity and range of adverse pregnancy outcomes.1 less concern about weight gain.9,11,12 Quitting Smoking causes obstetric and fetal before conception or in the first trimester results complications and there is growing in similar rates of adverse pregnancy outcomes, evidence of serious harm extending into compared with non-smokers;5 however quitting childhood and even adulthood (Table 1). at any time during pregnancy produces health Unfortunately, most smokers who become benefits.13 Quitting before pregnancy also allows pregnant continue to smoke and most of the use of the full range of pharmacotherapies. those who quit relapse after delivery.2,3 Continuing smokers Pregnancy is a window of opportunity for health In Australia, 14.5% women report smoking while professionals to help smokers quit.4 Women are pregnant and 1 in 6 of these smokers quits before motivated to protect their baby’s health, and delivery.3 The real prevalence of smoking is likely quitting smoking during pregnancy reduces the risk to be higher, as up to 25% of pregnant smokers do of complications.4–6 However, general practitioners not disclose their smoking status,14 often because (GPs) are missing many opportunities to intervene.7 of the social stigma.15 46 REPRINTED FROM AUSTRALIAN FAMILY PHYSICIAN VOL. 43, NO. 1–2, JANUARY– FEBRUARY 2014 Management of smoking in pregnant women CLINICAL Smoking during pregnancy is strongly Table 1. Pregnancy-related health effects of smoking associated with socioeconomic disadvantage11 Health effect Comments and is particularly prevalent in Aboriginal and Fertility Delayed conception 2 months on average55 Torres Strait Islander populations (see below). Smoking is also a marker for mental illness and Infertility: female 60% increased risk of infertility 56 almost 50% of pregnant smokers have a mental (OR 1.6) health disorder of some kind.16 Smoking rates Infertility: male Decreased semen volume, are higher in young women and 37% of teenage sperm number and increased 1 mothers smoke during pregnancy.3 abnormal forms Assisted reproduction 44% reduced odds of a live Postpartum relapse birth per cycle (OR 0.54)57 Most mothers who quit smoking during Obstetric Spontaneous miscarriage OR 1.81 pregnancy resume smoking within 6 months Preterm birth (<37 wks) ‘twice as great’1 of delivery and about 70% relapse within 12 Placenta previa OR 2.11 months.2 One reason for the high relapse rate is 1 that pregnant women often report suspending Placental abruption OR 1.6 their smoking only for the fetus and plan to Stillbirth OR 1.1–3.21 17 resume smoking after the birth. Ectopic pregnancy OR 2.51 Stress in the postpartum period arising from Premature rupture of OR 2.11 lack of sleep, caring for the infant, postnatal membranes depression and concerns about weight gain are 1 also likely contributors to the high relapse rate. Pre-eclampsia OR 0.51 (49% risk reduction) Other factors include having a smoking partner, Fetal Growth restriction 200 g lighter on average1 a higher smoking level before pregnancy, older Low birth weight (<2500 g) OR 3.0 (white women)1 age and socioeconomic disadvantage.18 Small for gestational age OR 3.8 >35 years 1 Aboriginal and Torres (<35 years = ns) Strait Islander pregnant Birth defects Limb reduction defects, clubfoot, oral clefts, eye defects women and gastrointestinal effects Aboriginal and Torres Strait Islander pregnant (OR 1.25–1.50). Also many women need special consideration. One in other smaller effects58 two (49.3%) Aboriginal and Torres Strait Child and adult SIDS OR 2.2559 Islander women smoke while pregnant3 and Type 2 diabetes OR 1.160 there may be concomitant use of cannabis.19 26 Many Indigenous pregnancies are unplanned; Obesity OR 1.52 women often present late to antenatal care and Hypertension 1.5–5.4 mm Hg increase60 20,21 have fewer antenatal visits. As a result, HDL 0.14 mmol/L decrease61 opportunities for early smoking cessation Nicotine dependence Double the risk62 intervention may be missed. Owing to the normalisation of smoking Respiratory Asthma, lower respiratory infection, decreased lung in Aboriginal and Torres Strait Islander function63 households, it is difficult for pregnant women Cognition Impaired academic to avoid other smokers and obtain support from 22 performance and cognitive family and partners. Smoking is often linked abilities64 to difficult life circumstances and high levels Behaviour Conduct disorder, ADHD, of stress. Reduced cigarette consumption is a antisocial behaviour65 frequent occurrence, as cessation is perceived as ‘too hard’. Few Aboriginal and Torres Psychiatric disorders Significant increase for most psychiatric disorders in early Strait Islander women maintain abstinence adulthood66 postpartum. For a more detailed review see OR = odds ratio; ns = not significant; HDL = high density lipoprotein Gould et al.23 REPRINTED FROM AUSTRALIAN FAMILY PHYSICIAN VOL. 43, NO. 1–2, JANUARY– FEBRUARY 2014 47 CLINICAL Management of smoking in pregnant women Health effects of smoking Studies in animals suggest that nicotine immediately after breastfeeding is preferred as in pregnancy is toxic to the fetal brain and impairs lung it allows more time for the nicotine and other The most common adverse fetal outcomes are development. Many other toxic compounds, chemicals to leave the breast milk before the growth restriction and preterm birth, both of including cyanide, polycyclic aromatic next feed.31 Encouraging pregnant women to which can lead to a range of serious health hydrocarbons, benzene and heavy metals such as breastfeed may help them to remain abstinent effects5 (Table 1). Nicotine reduces placental lead and cadmium cross the placenta.27 postpartum.31 blood flow and carbon monoxide lowers oxygen Non-smoking pregnant women are also availability to the fetus. The resulting decrease at risk from second-hand smoke, which Smoking interventions in in nutrient and oxygen delivery to the fetus leads increases the risk of stillbirth and congenital pregnancy to growth restriction.24 Carcinogens have also abnormalities,28 and reduces the birth weight by Interventions during pregnancy are modestly been implicated in low birth weight.25 Babies 33 g or more.29 effective and assist six in every 100 smokers with low birth weight experience rapid catch-up to quit.6 Many lighter smokers quit unaided growth that can result in obesity and chronic Lactation when they find out they are pregnant and the diseases, such as coronary artery disease, Women who smoke may produce less milk30 remaining smokers may need more intensive diabetes mellitus and hypertension.26 and are less likely to breastfeed.31 Smoking treatment.11,32 The Australian Smoking Cessation guidelines state that neither of the two prescription medicines for smoking cessation, Table 2. Resources for general practitioners and patients varenicline and bupropion, has been shown to be General practitioner resources effective or safe in pregnant and breastfeeding • RACGP. Supporting smoking cessation: a guide for health professionals (www.racgp. smokers, and they are not recommended.32 org.au/your-practice/guidelines/smoking-cessation/) • Department of Health and Ageing (DOHA). Clinical Practice Guidelines Antenatal Identify pregnant smokers Care (www.health.gov.au/internet/publications/publishing.nsf/Content/clinical-