'Snus' Smokeless Tobacco Unsafe for Pregnant Mothers

Pregnant women who use a form of smokeless tobacco known as “snus” may increase their risk of stillbirths, according to a new Swedish study, Reuters reported Sept. 17.

Although “snus” (also known as moist snuff) is marketed in the United States, it has been especially popular in Sweden, where use is on the rise among women in their childbearing years. Because it had been linked to lower risk of heart attack and cancer compared to cigarettes, it had gained a reputation as being safer than cigarettes. 

The researchers used data from a Swedish birth register on nearly 611,000 women pregnant between 1999 and 2006. They compared the 58,502 tobacco smokers they found with the 7,629 who used snus and the 504,531 who did not use tobacco.

They found that snus users were 60 percent more likely than non-users of tobacco to have a stillbirth — defined as loss of the pregnancy at week 28 or later — and they were more than twice as likely to have a preterm stillbirth (delivering before the 37th week). By contrast, light smokers (nine or fewer cigarettes per day) were 40 percent more likely to have a stillbirth, and heavy smokers were nearly two-and-a-half times as likely to do so.

“[U]sing moist snuff is not a safe way to quit smoking when you are pregnant,” said Dr. Anna-Karin Wikstrom, of Karolinska University Hospital Solna in Sweden, the lead reseacher.

While it is not yet known why snus causes stillbirths, nicotine is the likely culprit, according to Dr. Gregory N. Connolly, who directs the Tobacco Control Research Program at the Harvard School of Public Health. He noted that American forms of snus, such as Camel Snus and Marlboro Snus, have lower levels of nicotine than those marketed in Sweden. Therefore, it is not clear if the Swedish findings can be generalized to the United States. 

Connolly also pointed out that the study did not differentiate between light and heavy users, so it was not clear whether the women's risk of stillbirth varied based on the amount of snus they used. 

The study appeared online Aug. 27, 2010, in Epidemiology.