Passive smoking in pregnancy

Editor—In the issue of 18 October several original papers and an editorial by Davis¹ highlighted the importance of passive smoking—an issue that deserves to receive widespread publicity. The problem of passive smoking in pregnancy remains underappreciated by both healthcare workers and the public.

Smoking in pregnancy is associated with numerous complications for both mother and baby. Effects start in utero, resulting in increased perinatal mortality and morbidity and the sudden infant death syndrome.² Many pregnant women appreciate that their own cigarette smoking may have ill effects on the fetus, but limited information is available to pregnant women on the potential harm of their inhaling the cigarette smoke of others. Meconium analysis indicates that nicotine metabolite concentrations in infants of passive smokers are not significantly different from those in infants of active light smokers.³ Fetal exposure to tobacco smoke may therefore be substantial even as a result of maternal passive smoking.

We recently conducted a small study to determine the prevalence of passive smoking among pregnant women at home and in the workplace and how many women received advice against smoking.⁴ Data were collected prospectively by anonymous self administered questionnaire from 113 women attending a public antenatal clinic. The response rate was 100%. Sixty women were primiparous, 48 were single, and 62 were in employment outside the home during their pregnancy. Forty seven women smoked, 26 were ex-smokers, and 40 had never smoked. Nine of the 26 ex-smokers had stopped just before or during the current pregnancy. Overall, 81 women were exposed to passive smoking during pregnancy (72%), 41 being exposed at home only, 18 at work only, and 22 at home and at work. Forty of the 62 women who were employed were exposed to passive smoking. Most smokers were also exposed to passive smoking (38 out of 47). Advice against smoking had been given to 56 women during their current pregnancy and to 28 at some stage in the past, but 29 women had never received such advice.

Our results indicate that the prevalence of passive smoking in pregnancy is high. This study relied on a questionnaire as a measure of maternal passive smoking and may have underestimated the extent of the exposure. Although the number studied was small, this report indicates that passive smoking in pregnancy may be a bigger problem than is generally appreciated. The need to highlight the risk of environmental tobacco smoke should not be restricted to smokers, and we recommend that it should be discussed with all pregnant women at booking.