Swedish snus can be as damaging to the fetus as smoking

While it is well known that smoking while pregnant can damage the fetus, the effects of using Swedish snus (oral moist snuff) have been more mooted. Now, a new thesis from Karolinska Institutet in Sweden shows that using snus while pregnant carries the same level of risk as smoking as regards to stillbirth, preterm birth, cleft lip and palate, and neonatal apnea. However, it pays off to quit using snus early in the pregnancy, before the first visit at the antenatal care, as doing so gives no observable increase in risk.

Anna Gunnerbeck at Karolinska Institutet’s Department of Women’s and Children’s Health has recently defended her thesis on how the nicotine consumption of pregnant women affects their unborn babies. Cigarettes contain some 4,000 substances, while Swedish snus contains almost only nicotine. Basing research on women who use snus provides unique information about what kind of damage nicotine does to the fetus.

Her doctoral thesis is based on data from the National Board of Health and Welfare’s Medical Birth Register, which provides information on the health of mother and baby for effectively all pregnancies in Sweden from the point of entry into antenatal care to a month after birth.

Not a healthier alternative

Snus gives even higher doses of nicotine than cigarettes and can be taken more frequently. By charting the tobacco habits of pregnant women and the state of health of their babies, Anna Gunnerbeck’s research group found that using snus carried an equally high risk of stillbirth, preterm birth, cleft lip and palate and neonatal apnea.

“Snus is often promoted as a healthier alternative to smoking, and it may be for adult users,” says Dr Gunnerbeck. “But the nicotine in the snus can damage fetuses. Young women who start using snus are unaware of the risk they subject their unborn babies to when they use snus while pregnant.”

Important to reach out to young women

Anna Gunnerbeck's research also shows that the health risk to the fetus is significantly reduced if the mother stops using snus very early in her pregnancy.

“If you stop using snus as soon as you find out you’re pregnant, the risk of fetal damage doesn’t increase,” continues Dr Gunnerbeck. “So it’s important that we reach out with this health message to young people. Ideally before they start using tobacco, since the nicotine in snus, like that in cigarettes, is highly addictive and very hard to give up.”

Sweden is uniquely placed to study the effects of nicotine in pregnancy given that snus has been in widespread use here for such a long time. The results are, however, of global interest since e-cigarettes and nicotine patches are often marketed as healthy alternatives to smoking, and the use of the former is increasing in many countries.

The research was financed by Karolinska Institutet and Stockholm County Council.

Anna Gunnerbeck defended her thesis "Prenatal nicotine exposure and effects on the health of the newborn" on 21 April 2017.