Pregnancy And Environmental Tobacco Smoke

More than half of women smokers do not quit during pregnancy. Nevertheless, this condition provides an ideal “teachable moment” with patients who might not know the full implications of environmental smoke damage.

In 2001 the Surgeon General of the United States issued a report confirming that “smoking is the leading known cause of preventable death and disease among women.”¹ The report links active smoking in women to adverse health outcomes ranging from cancer to reproductive problems, and underscores the dangers from exposure to environmental tobacco smoke (ETS) for women, fetuses, and children.

Despite decades of antismoking messages, many targeting women and girls, more than 22% of women in the United States are smokers. Smoking and exposure to burning tobacco products pose special risks for pregnant women, yet, surprisingly, more than half of all women smokers do not quit during pregnancy. Estimates of the percentage of pregnant women who continue to smoke range from 12.9% to more than 27%.² Pregnant women also face significant health risks from environmental tobacco smoke in their homes, at work, and in other public settings.

Environmental tobacco smoke, commonly known as secondhand smoke, is a complex mixture of chemicals generated during the burning of tobacco products. ETS consists of mainstream and sidestream smoke. Mainstream smoke is composed of substances given off from a burning cigarette when a smoker exhales. Sidestream smoke is the material that enters the atmosphere from the end of a burning cigarette. Sidestream smoke is the principal contributor to ETS because it is not filtered and has significantly higher concentrations of toxic and carcinogenic compounds. When compared with mainstream smoke, sidestream smoke has twice as much tar and nicotine; three times as much benzo(a)pyrene, a carcinogen; almost three times as much carbon monoxide; and three times as much ammonia.³

More than 4,000 substances have been identified in mainstream smoke, and approximately 400 compounds have been measured in both mainstream and sidestream smoke. More than 50 of these compounds are known carcinogens. In addition, several tobacco compounds, including carbon disulfide, carbon monoxide, lead, nicotine, cadmium, and toluene, have been recognized as developmental or reproductive toxicants.⁴ In the form of environmental tobacco smoke, these chemicals and compounds are estimated to contribute to 3,000 deaths from lung cancer and 35,000 deaths from heart disease each year in nonsmokers along with as many as 300,000 respiratory tract infections in infants and children.⁵

Women, Pregnancy, and ETS
Tobacco smoke affects nearly every system in the body, resulting in higher rates of disease and premature death. Women smokers are more likely than nonsmokers to die from emphysema and chronic bronchitis.⁶ For women of childbearing age, ETS and smoking form a unique threat, increasing the risk of many reproductive problems, including difficulty conceiving, infertility, ectopic pregnancies, stillbirths, miscarriages, and cervical cancer.⁷ Pregnant women exposed to ETS also have been found to have impaired lung function, higher overall rates of asthma, and more severe bouts of asthma.⁸

Environmental tobacco smoke is transported from the mother through the placenta, hampering the delivery of essential nutrients and oxygen to the fetus. Fetal hypoxemia is believed to be a major contributor to poor health outcomes, including low birth weight and neurotoxicity. Two major pathways associated with these outcomes have been identified: acute nicotine-induced fetal hypoxemia following maternal vasoconstriction and reduced uterine perfusion, and binding of carbon monoxide to fetal hemoglobin to form carboxyhemoglobin (HbCO) in the blood and amniotic fluid, thereby reducing the available oxygen supply to the fetus. It has been estimated that maternal HbCO levels of 10%, which can be observed in a two-pack-per-day smoker, would result in a decrease in available oxygen supply to the fetus similar to a reduction of blood flow by 60%.⁹

Exactly how much of the environmental tobacco smoke reaches the fetus is not fully known; however, there is an objective measure using nicotine and cotinine levels (cotinine is a metabolite of nicotine). These biomarkers can be tracked in the body fluids of the mother and fetus.⁴ It appears that a dose-response relationship exists between ETS and adverse health effects, much like that found for many other toxicants. Fetuses, babies, and children appear especially vulnerable to ETS. Some studies have shown as much as twice the levels of cotinine in children compared with adults.¹⁰

Babies that were exposed to ETS during pregnancy are at risk of slightly lower birth weight, some increased intrauterine growth retardation, and SIDS, compared with nonexposed babies.^1,7,9 Studies also have shown that the 38% of young children (from 2 months to 5 years of age) who are exposed to ETS at home suffer from more frequent lower respiratory tract infections, including bronchitis and pneumonia; increased fluid in the middle ear; more upper respiratory tract irritations; a small but significant reduction in lung function; more meningococcal infections; and an increase in number of cases, individual episodes, and severity of symptoms of asthma.^7,11,12 Further, the Campaign for Tobacco-Free Kids¹³ notes that maternal smoking during pregnancy and exposure to ETS raise the risk of infant death from perinatal disorders; cleft palates and lips; eye problems; colic, wheezing, and respiratory disorders; cancer-causing agents in infants’ blood, potentially carcinogenic genetic mutations, and childhood leukemia; and learning, developmental, and behavioral problems.

The Role of RTs
Given the growing body of scientific evidence on the impact of smoking and ETS, health professionals in the United States and throughout the world are calling for more smoking prevention, cessation, and treatment programs for women, particularly during the highly vulnerable time of pregnancy. Also, health advocates are demanding more supportive policies, legislation, and smoke-free environments to protect pregnant women and their unborn children from exposure.

RTs can contribute to this vital effort by being informed about the clinical presentation of exposure to ETS in pregnant women. Clinical effects of ETS can be as subtle as increased coughing, increased sputum production, chest discomfort, and reduced lung function. But this does not hold true for the asthmatic since cigarette smoke is a common trigger. ETS can cause serious problems for pregnant asthmatics. Exposure to burning tobacco at home, at work, and in public settings can mean a 40% to 60% increased risk of exacerbation of symptoms compared with pregnant women who are not exposed to ETS.⁷

RTs also can take the lead at work to reduce ETS for pregnant women and their offspring, including informing and training coworkers. (See sidebar, this page.)

Finally, RTs can make pregnant women a priority in their practices and facilitate changes in knowledge, perceptions, and behavior related to ETS. Health promotion specialists regard pregnancy as a unique time in women’s lives, when they personalize susceptibility and their concern for their unborn children makes them more receptive to information, advice, and behavior change.¹¹ The 2001 Surgeon General’s Report on Women and Smoking showed, for example, that women smokers are more likely to quit during pregnancy than at any other period in their lives.¹ RTs can capitalize on this “teachable moment” to inform, change perceptions, and motivate behavioral and environmental change among patients.¹⁴ (See “Teachable Moments,” page 32.)

Even patients knowledgeable about the dangers of smoking may not fully realize the health consequences of ETS for pregnant women and their offspring. Addressing this is not easy. Health practitioners are up against false messages and massive advertising campaigns by tobacco companies encouraging women to smoke and omitting information about the dangers of ETS exposure. They also are competing with the addictive qualities of tobacco. Yet, as an old African proverb says, “to educate a woman is to educate a family, a nation.” By making pregnant women a priority in their practices, RTs can reach at least two people at once—the woman and her unborn child. They also can foster healthier environments for family members, friends, and co-workers.

Roberta B. Hollander, PhD, MPH, is interim chairperson and professor of health education, Department of Health, Human Performance and Leisure Studies, Howard University, Washington, DC. Donna Freeman, RRT, has 23 years of experience as a respiratory therapist and is completing her master of science degree in health education at Howard University. Autumn Saxton-Ross is a graduate student completing her master of science degree in health education at Howard University. She teaches courses in women’s health at Howard.

References:
1. US Department of Health and Human Services. Women and Smoking: A Report of the Surgeon General, Executive Summary. Washington, DC: US Government Printing Office; 2001.
2. Beck LF, Morrow B, Lipscomb LE, et al. Prevalence of selected maternal behaviors and experiences, pregnancy risk assessment monitoring system (PRAMS), 1999. MMWR CDC Surveill Summ.2002;51(2):1-27.
3. Insel PM, Walton RT. Core Concepts in Health. 9th ed. Boston:McGraw Hill; 2002:174.
4. Health Effects of Exposure to Environmental Tobacco Smoke, the Report of the California Environmental Protection Agency, Smoking and Tobacco Control. Monograph 10. US Department of Health and Human Services, National Institutes of Health, National Cancer Institute. 1999. NIH Pub No. 99-4645.
5. US Department of Health and Human Services, Centers for Disease Control and Prevention. Public health demands continuing progress in tobacco control. Chronic Disease Notes & Reports. 2001;14(3):2-3.
6. American Lung Association Fact Sheet: Women and smoking, June 2002. Available at: http://209.208.
153.222/tobacco/ women_ factsheet99.html.
7. Action on Smoking and Health (November 2002). Passive smoking: a summary of the evidence. Available at: http://www.ash.org. uk/html/passive/html/passive.html.
8. Janson C, Chinn S, Jarvis D, et al. Effect of passive smoking on respiratory symptoms, bronchial responsiveness, lung function, and total serum IgE in the European Community Respiratory Health Survey: a cross-sectional study. Lancet.2001;358:2103-2109.
9. Ferrence R, Slade J, Room R, Pope M. Nicotine and Public Health. Washington, DC: American Public Health Association; 2000.
10. US Centers for Disease Control and Prevention. Second National Report on Human Exposure to Environmental Chemicals, General Fact Sheet. Available at: http://www.cdc.gov/exposurerep
ort/genfactsheet.htm.
11. Groner JA, Ahijevych K. The impact of a brief intervention on maternal smoking behavior. Pediatrics. 2000;105:267-271.
12. Blizzard L, Ponsonby AL, Dwyer T, Venn A, Cochrane A. Parental smoking and infant respiratory infection: how important is not smoking in the same room with the baby? Amer J Public Health. 2003;93:482-488
13. Harm Caused by Pregnant Women Smoking or Being Exposed to Secondhand Smoke. Washington, DC: Campaign for Tobacco Free-Kids; October 30, 2001.
14. Green LW, Kreuter MW. Health Promotion Planning: An Educational and Ecological Approach. 3rd ed. Mountain View, Calif: Mayfield Publishing Company; 1999.
15. Health & Economic Impact: Smoking Cessation for Pregnant Women. US Department of Health and Human Services, Centers for Disease Control and Prevention; July 2002.