Feb. 29, 2008 Findings from a National Institute of Health study indicate that rates of tobacco use during pregnancy, as well as exposure of pregnant women and their young children to secondhand smoke, are significant threats to health in several low and middle-income countries. In a few of the countries sampled, including some in Latin America, rates of tobacco-related exposures may already be high enough to warrant substantial concern.
Findings from the study, which is the first to examine pregnant women's tobacco use, second-hand smoke exposure and attitudes toward women's tobacco use in multiple developing countries, will appear in the American Journal of Public Health.
Historically, the prevalence of smoking among women in the developing world has been very low, in part because of strong cultural constraints against women's tobacco use. "This study indicates that public health officials in developing nations should take immediate steps to prevent and reduce tobacco use and secondhand smoke exposure among pregnant women," said Duane Alexander, M.D., Director of the National Institute of Child Health and Human Development (NICHD). "This should include efforts to better understand the scope of the problem, so as to best direct public health interventions."
The study was conducted by an international team of investigators, including researchers from the National Cancer Institute (NCI) and NICHD, two NIH institutes. The researchers conducted the study at ten sites in the NICHD Global Network for Women's and Children's Health Research, which focuses on improving maternal and child health in the developing world.
Approximately 8,000 pregnant women were surveyed at five sites in Latin America (Argentina, Uruguay, Ecuador, Brazil and Guatemala), two sites in Africa (Zambia and the Democratic Republic of the Congo) and three sites in Asia (two in India and one in Pakistan). The survey looked at pregnant women's use of tobacco products (cigarettes and smokeless tobacco), their perceptions of the social acceptability of tobacco use for women, and exposure to secondhand smoke experienced by them and their young children.
"Preventing an increase in tobacco use by women in the developing world is widely recognized as a significant public health opportunity," said lead author Michele Bloch, M.D., Ph.D., of NCI's Tobacco Control Research Branch. "Our results demonstrate that pregnant women's tobacco use and exposure to secondhand smoke threaten to impede or reverse ongoing efforts to improve maternal and child health in the developing world."
Because few studies have looked at tobacco use and secondhand smoke exposure among pregnant women in low and middle-income countries, the researchers conducted this investigative survey in nine developing nations to get a preliminary look at the magnitude of the problem. The researchers found as many as 18 percent of pregnant women currently smoked cigarettes, up to one-third used smokeless tobacco, and as many of half were regularly exposed to secondhand smoke in the nations studied. The researchers also found evidence that in some countries where pregnant women's tobacco use is currently low, rates of smoking during pregnancy could increase dramatically if barriers to women's tobacco use were removed.
Uruguay and Argentina had the highest levels of smoking during pregnancy across all ten study sites (18 percent and 10 percent respectively). While the three other Latin American sites reported fewer women smoking during pregnancy, all had large numbers of respondents who had tried cigarettes at least once. If women's smoking were to become more culturally acceptable, these other sites would be poised for much higher levels of smoking by pregnant women.
In the Indian sites, one-third of all pregnant women used smokeless tobacco in Orissa and about twenty percent of pregnant women in Karnataka were often exposed to secondhand smoke. The highest levels of secondhand smoke exposure were found in Pakistan, where about half of all pregnant women and their young children were frequently or always exposed to secondhand smoke. About one in ten pregnant women at the site in Pakistan reported that they had tried cigarette smoking.
In the Democratic Republic of the Congo, 40 percent of respondents reported that they had tried smokeless tobacco at least once, and six percent had used smokeless tobacco while pregnant. About 14 percent of women in the Democratic Republic of the Congo had tried cigarettes, as had about seven percent of women from Zambia.
The researchers recognize that the study has some limitations. For example, the data were collected by self-report through face-to-face interviews, and because tobacco use by women is a heavily stigmatized behavior, the study findings may actually underestimate the scope of the problem. Differences among study participants in geographic setting, literacy levels, employment status, and the presence of tobacco users in the household may also have contributed to differences in reported tobacco exposure.
Pregnant women are a priority population for tobacco prevention efforts because tobacco use poses serious risks to fetal and maternal health. Smoking during pregnancy causes a number of problems, including preterm delivery, low birth weight and sudden infant death syndrome. For the mother, cigarette use can lead to lung and other cancers, coronary heart disease, stroke, and chronic obstructive pulmonary diseases. Smokeless tobacco use can lead to oral and pancreatic cancers. Secondhand smoke causes lung cancer and heart disease in adults, and can lead to serious illnesses, such as bronchitis and pneumonia in infants and children.
"Where tobacco use rates are still low, we have the opportunity to avert an increase in tobacco use among women, especially pregnant women, in the developing world," said Linda Wright, M.D., Scientific Director of the Global Network, in NICHD's Center for Research for Mothers and Children. "These data highlight the urgent need to adopt proven measures to prevent and control tobacco use -- both cigarettes and smokeless tobacco -- and secondhand smoke exposure of women and girls worldwide."
Funding for this research came from NICHD, NCI, the U.S. Department of Health and Human Service's Office on Women's Health, and the Bill and Melinda Gates Foundation.
Journal reference: Bloch M, Althabe F, Onyamboko M, Kaseba-Sata C, Castilla EE, Freire S, Garces AL, Parida S, Goudar SS, Kadir MM, Goco N, Thornberry J, Daniels M, Bartz J, Hartwell T, Moss N, Goldenberg R. Tobacco Use and Secondhand Smoke Exposure During Pregnancy: An Investigative Survey of Women in 9 Developing Nations. American Journal of Public Health, Vol. 98, No. 4. Published online February 28, 2008.
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