Montreal, Quebec—Pharmacists might want to caution expectant mothers about the risks of using fluconazole to treat vaginal yeast infections.

A report in CMAJ (Canadian Medical Association Journal) linked the oral antifungal drug to higher rates of miscarriage.

Background information in the article adds that although topical treatments are first line for pregnant women with fungal infections, oral fluconazole is commonly used during pregnancy, as well.

To reach their conclusions, University of Montreal–led researchers looked at data on 441,949 pregnancies from the Quebec Pregnancy Cohort between 1998 and 2015. That information was linked to filled prescriptions listed in the Quebec Prescription Drug Insurance database.

“Our study shows that taking any dose of oral fluconazole while pregnant may be associated with a higher chance of miscarriage,” explained Anick Bérard, PhD, of the Université de Montréal in Quebec. “Taking higher doses of fluconazole over 150 mg in early pregnancy may be linked to a higher chance of a newborn with a heart defect.”

Specifically, the study team sought to assess the effect of exposure to low and high doses of fluconazole during pregnancy on the occurrence of spontaneous abortions, major congenital malformations, and stillbirths.

For purposes of the study, low-dose was defined as 150 mg or less, while high dose was defined as greater than 150 mg. The researchers note that most, 69.5%, women exposed to fluconazole in pregnancy received the common single therapeutic dose of 150 mg.

Results indicate that use of oral fluconazole during early pregnancy was associated with an increased risk of spontaneous abortion compared with no exposure (adjusted odds ratio [OR] for 345 cases exposed to low-dose treatment 2.23, 95% confidence interval [CI], 1.96-2.54; adjusted OR for 249 cases exposed to high-dose treatment 3.20, 95% CI, 2.73-3.75).

Researchers report, however, that use of fluconazole during the first trimester did not increase the risk of overall major congenital malformations, although exposure to a high dose of the drug early in pregnancy was associated with an increased risk of cardiac septal closure anomalies (adjusted OR 1.81, 95% CI, 1.04-3.14; 13 exposed cases) versus no exposure.

The study found no association between exposure to fluconazole during pregnancy and the risk of stillbirth.

“Any maternal exposure to fluconazole during pregnancy may increase risk of spontaneous abortion and doses higher than 150 mg during the first trimester may increase risk of cardiac septal closure anomalies,” study authors conclude, adding that their results are consistent with other research. They called for more studies because participant sizes have been small.

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