"We know that nicotine hampers the blood flow to the baby," says researcher Anna-Karin Wikström to Swedish Radio News.
In the so far biggest study into the matter, the researchers found that the risk of a foetus dying in the womb is 46 per cent higher if the mother is using the snuff during pregnancy, compared to if the woman is not. For smoking mothers, the risk is 59 higher.
The findings mean that it is not a good idea for pregnant women to cut down on smoking by using "snus" or nicotine patches or nicotine chewing gums instead.
"Nicotine in medical products contain a lower concentration than if you are using wet snuff or smoking, so we cannot say for sure whether this is dependant on the dosage. But naturally we have to advice caution when it comes to nicotine medicine," says Anna-Karin Wikström.
The study does show positive effects among pregnant women who stop smoking or using the wet snuff. "if you stop suing wet snuff in the beginning of pregnancy, the increased risks of premature birth or for the foetus to die in the womb disappear completely," says Anna-Karin Wikström.