Maternal use of Swedish snuff (snus) and risk of stillbirth

Swedish snuff has been discussed internationally as a safer alternative to tobacco smoking. International cigarette manufacturers are promoting new snuff products, and the use of Swedish snuff is increasing, especially among women of childbearing age. The effect of Swedish snuff on pregnancy complications is unknown.

In this population-based cohort study, we estimated the risk of stillbirth in snuff users (n = 7629), light smokers (1-9 cigarettes/day; n = 41,488), and heavy smokers (≥10 cigarettes/day; n = 17,014), using nontobacco users (n = 504,531) as reference.

Compared with nontobacco users, snuff users had an increased risk of stillbirth (adjusted odds ratio = 1.6 [95% confidence interval = 1.1-2.3]); the risk was higher for preterm (<37 weeks) stillbirth (2.1 [1.3-3.4]). For light smokers, the adjusted odds ratio of stillbirth was 1.4 (1.2-1.7) and the corresponding risk for heavy smokers was 2.4 (2.0-3.0). When we excluded women with preeclampsia or antenatal bleeding and infants who were small for gestational age, the smoking-related risks of stillbirth was markedly attenuated; the elevated risk for snuff users remained the same level.

Use of Swedish snuff during pregnancy was associated with a higher risk of stillbirth. The mechanism behind this increased risk seems to differ from the underlying mechanism in smokers. Swedish snuff does not appear to be a safe alternative to cigarette smoking during pregnancy.