It has long been known that smoking is associated with an increased risk of miscarriage. A study from Örebro University, The association of smoking, use of snuff, and preconception alcohol consumption with spontaneous abortion: A population-based cohort study published in Acta obstetricia et gynecologica Scandinavica, shows that the increased risk also applies to those who use snuff. In the study, 6,6 percent of pregnancies ended in miscarriage. For those who smoked 1-9 cigarettes per day, the risk of being one of the victims increased by 11 percent, for those who smoked ten cigarettes per day or more, the risk increased by 38 percent, and for snuff users, 28 percent.
– The most interesting thing about the study was that we don't know how much snus each snus user uses per day. There is everything from those who snus a little every day, to those who have a portion of snus in their mouth all the time, when they take one out they put a new one in. But despite that, the risk of miscarriage was greater for snus users than for those who smoked 1-9 cigarettes per day, says Yvonne Skogsdal, midwife and researcher at the Department of Health Sciences, Örebro University.
The study is based on data from just over half a million women's first visits to midwifery clinics, during the period July 2014 to July 2018.
Few of the women smoked at the first visit to the midwife's office, 5,1 percent, and even fewer used snuff, 1,2 percent. The researchers adjusted for explanations other than tobacco use for a higher risk of miscarriage.
– When we calculated the increased risk for snus users and smokers, we took into account other factors that we also know can affect the risk of miscarriage, such as high BMI, smoking (for those who used snus), snus (for smokers), alcohol use before pregnancy, social factors, etc. It is difficult to be completely sure that we have adjusted for everything that can affect the risk of miscarriage. There may be something else that we are not aware of, or that we did not have access to control. But it has been known for a long time that smoking is associated with miscarriage. Several studies have shown this.
Yvonne Skogsdal is not aware of any other study on the risk of miscarriage for snus users, but she does not think the results are surprising.
– Since snus is also a tobacco product, it provides support for the fact that snus is also associated with miscarriage, says Yvonne Skogsdal.
The study is based on data from 2014-2018, when white nicotine snus had not yet become widespread. How should we view the risks of miscarriage with it, compared to brown snus?
– There are no studies on white snus and miscarriage, and we also do not know how many pregnant women use white snus. But when you read other countries' interpretations of other nicotine products such as e-cigarettes and water pipes, which there are also few studies on, you know that nicotine crosses the placenta to the fetus, and then you can probably expect that it will generally pose the same kind of risks as other nicotine products. You should bear that in mind, but of course it can differ between different products, says Yvonne Skogsdal.
