Many pregnant women suffer from vaginal fungal infections and are treated with a suppository. But some women are treated with an oral pill that new research suggests is associated with an increased risk of miscarriage. (Photo: Shutterstock)

Pills to fight fungal infections increase risk of miscarriage

Pregnant women who take fluconazole pills to treat vaginal fungal infections are more likely to miscarry than women who take a suppository, shows new research.

Pregnant women who contract a vaginal fungal infection are typically treated with a vaginal suppository. But some of these women are prescribed the oral tablet fluconazole, which is now linked to an increased risk of spontaneous miscarriage, according to new research published in the scientific journal JAMA.

Whilst comparatively few pregnant women are treated with fluconazole, the results are non the less important, according to lead-author Ditte Mølgaard-Nielsen, from the Statens Serum Institut, Denmark.

"It’s important that those who [treat] pregnant women are aware that we have found this risk,” says Mølgaard-Nielsen.

“If’s often a problem that there is very little knowledge about the drugs used during pregnancy, and therefore it’s appropriate to examine all the drugs that [pregnant] women take. Fluconazole is an obvious drug because vaginal fungal infection is something that many women suffer from during pregnancy," she says.

147 miscarriages among those treated with fluconazole

In the study, researchers collected data on all registered pregnancies over a 17-year period from 1997 to 2013.

Out of 1.4 million pregnancies, 3,315 women were treated with an oral fluconazole pill, and 147 of this group miscarried. This represents a 50 per cent higher risk of miscarriage than in women who underwent no treatment for fungal infections, or were treated with a suppository.

The result has surprised health scientists, even though suppositories are already their preferred form of treatment.

"We went to great lengths to complete a lot of analyses to ensure that it can’t be explained another way,” says Mølgaard-Nielsen. For example, the first trimester is a particularly risky period.

Still some doubt as to whether the drug leads to miscarriage

The increased risk of miscarriage in pregnant women treated with fluconazole, does not yet confirm that the drug itself is to blame.

Mølgaard-Nielsen does not yet know why these women were treated with a pill instead of a suppository, but depending on what the reasons are, it could affect the conclusions.

"The problem is that we have no indication of why they’ve been given fluconazole. If it’s because they have a severe infection, or because the local treatment didn’t work, then this could’ve influenced their increased risk of miscarriage. We can’t rule this out,” says Mølgaard-Nielsen.

“But if it was pure chance that determined whether they received a local or oral treatment, then this could indicate that it has something to do with the drug," she says.

Professor Ulrik Schiøler Kesmodel of the gynaecological and obstetric department at Herlev and Gentofte Hospital, Denmark, was not involved in the research himself, but he has read it and describes it as thorough and well executed.

But he points to a number of other factors that Mølgaard-Nielsen and colleagues did not consider: alcohol intake, smoking and coffee habits, and the women’s weight were not considered, though all are known to have some influence on the risk of miscarriage.

"It’s not certain that it would change anything, but we know that the risk of miscarriage and stillbirth is greater if you have a large coffee consumption, daily consumption of alcohol, if you smoke, or if you’re overweight or obese,” says Kesmodel.

“It’s important to deal with these, because it could remove the entire association shown here," he says.


Read the Danish version of this story on

Translated by: Catherine Jex

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