Prenatal Exposure to Smokeless Tobacco Just as Dangerous as Cigarette Exposure
A popular form of smokeless tobacco in Sweden, known as ‘snus,’ may cause the same rate of stillbirth deliveries among pregnant women who use the product as those who use other forms of tobacco, according to a new epidemiological study.
‘Snus,’ otherwise known as ‘moist snuff,’ is a Swedish-based tobacco product that has become widely used by the Swedish population, especially among individuals of childbearing age. Snus is generally considered as a more socially acceptable form of tobacco use, and is thought to be less ‘harmful’ than cigarette smoking since toxins like carbon monoxide are not released into the environment and no spitting is involved as with other smokeless tobacco products. Snus itself contains lower level toxins called tobacco-specific nitrosamines and is believed to have lower risks of heart disease and cancer. Now with new evidence from researcher Anna-Karin Wikström from the Karolinska University Hospital Solna in Sweden and her colleagues, snus has been shown to be no ‘safe alternative’ to cigarettes despite its popular assumptions regarding its ability to snub one’s nicotine fix.
Although snus is most prevalent among the Swedish population, U.S. tobacco companies such as Camel and Marlboro have designed their own brands of ‘snus’ within recent years, and have market-tested their snus-like smokeless tobacco products among the American public. While smoking is well-known to cause serious risks during pregnancy—such as premature births, miscarriage, low birth weight, and stillbirth—the same risks of snus use are currently unknown. With the sale and use of snus gradually rising on a global scale, the Swedish research team decided to assess these snus-related risks and compare their hazardous potential to that of cigarette smoking.
Earlier this year, the same research team had published a study finding snus use during pregnancy to be associated with a higher risk of premature births compared to non-maternal use of tobacco products. In their most recent investigation, the researchers conducted a population-based cohort study using a national birth register in Sweden that contained the medical histories of hundreds of thousands of pregnant women who gave birth between the years 1999 and 2006. The researchers identified the women who were current snus users at the time of their pregnancy (7,629) as well as those who were light cigarette smokers (41,488). These two groups’ rates of stillbirth deliveries were compared to those of mothers considered as heavy smokers (17,014) and non-tobacco users (504,531) who served as the study’s control groups.
Overall, the researchers identified a total of 1,926 stillbirths (pregnancies lost after 28 weeks or more) among the study’s population, or almost 3% of all pregnancies. Compared to non-tobacco users, women who reported using snus during pregnancy had a 60% increased risk of stillbirth deliveries; the risk of stillbirth was more than doubled among women who used snus and had premature births. About 0.5% of women who reported using snus during their pregnancies experienced stillbirths (40 women out of 7,629). On the other hand, women who were non-tobacco users demonstrated the lowest risk of stillbirths among the study—only 0.3%—yet they belonged to the group with the largest population (1,386 women out of 504,531). Even after the researchers adjusted their findings by removing other risk factors that could contribute to stillbirth delivery, the risk of experiencing stillbirth due to snus use during pregnancy remained the same.
Mothers who had used other forms of tobacco experienced similarly high risks of stillbirth as the women who used snus during pregnancy. Women considered light smokers had a 40% increased risk of stillbirth in comparison to their non-tobacco using counterparts (172 women out of 41,488). Women who smoked heavily during their pregnancies had the highest risk of stillbirths among the study—making them 2.4 times more likely than their non-tobacco using counterparts. Among the 17,014 women considered heavy smokers, 0.7% (120 women) had experienced stillbirths.
Despite having lower levels of toxins, the commonality among snus products and cigarettes is the presence of nicotine, which is believed to have attributed to these women’s higher risk of stillbirth deliveries. However, further research will be needed to identify the exact underlying mechanism that is associated with stillbirths among snus users and those of cigarette users. Yet the results of the study proved to researchers that snus use, unlike the general assumption, are not safer to use than cigarettes during pregnancy. This latest finding will help the FDA determine the safety of newer snuff products that are beginning to be marketed within the U.S.
The researcher’s latest study is available online ahead of print in the journal Epidemiology.
Source: Reuters Health, Amy Norton, "Snus" Tobacco Linked to Still-Birth Risk, September 17, 2010
