Fluconazole antifungal medication during pregnancy does not increase overall birth defect risks

(RxWiki News) Women have to be especially careful about which medications they take during pregnancy. Many medications are fine, but others may pose a risk to the developing baby.

A recent study found that a particular antifungal medication does not appear to increase the risk of overall birth defects in children of mothers who take it during pregnancy.

The medication, fluconazole, is an antifungal medication known under the brand name Diflucan.

Past research has shown a risk for birth defects when high doses of fluconazole are taken by pregnant women, but this study looked at the possible effects of lower doses.

The study did find an increased risk for one particular type of heart defect among babies of mothers who took fluconazole, but the overall risk of that defect was still very low.

"Ask your OB/GYN about safe medications during pregnancy."

This study, led by Ditte Molgaard-Nielsen, MSc, of the Department of Epidemiology Research at Statens Serum Institut in Copenhagen, Denmark, looked at the risk for birth defects in babies of mothers who took fluconazole.

The study included 976,300 babies born in Denmark from January 1996 through March 2011.

Then the researchers used a national registry for prescriptions to identify which mothers had filled prescriptions for oral fluconazole, itraconazole and ketoconazole (all antifungals) during pregnancy.

The researchers looked specifically for 15 different birth defects that had been previously linked to antifungal medications in animal or observational studies.

These birth defects included cleft palate, an early fusing of the skull bones, cleft lip, other facial defects, middle ear defects, limb defects, having more than 10 fingers or toes, having fingers or toes fused together, a defect in the diaphragm, lung defects and several different heart defects.

A total of 7,352 women took fluconazole during pregnancy, and 968,236 women did not take any antifungals during pregnancy.

Most of the women (56 percent) taking fluconazole were prescribed a dose of 150 milligrams, and 31 percent took a dose of 300 milligrams.

The researchers did not find an overall increased risk for birth defects among the children of women who took fluconazole while pregnant.

Approximately 2.9 percent of the babies born to mothers who took fluconazole had birth defects, compared to 2.6 percent of women who did not take any antifungals during pregnancy.

The difference between these numbers was too small to be significant and could be due to chance.

Then the researchers looked specifically at each type of birth defect to see if fluconazole was linked to a particular condition.

For 14 of the 15 birth defects included in the study, there was no increased risk among the babies of mothers who took fluconazole during pregnancy.

For one birth defect, a heart defect called "tetralogy of Fallot," the researchers found an increased risk for babies born to mothers taking fluconazole.

A total of 0.1 percent of babies born to mothers who used fluconazole had this defect, compared to 0.03 percent of babies born to mothers not taking antifungals.

This means that approximately 10 in 10,000 babies born to mothers taking fluconazole had the defect, compared to 3 in 10,000 babies born to mothers not taking it.

The researchers therefore concluded that fluconazole in smaller doses does not pose an increased risk for all but one birth defect, which appears to have a slightly higher risk even though it's still very rare.

Andre Hall, MD, an OBGYN at Birth and Women's Care, PA in Fayetteville, NC, however, said this study does not change the need for caution in how fungal infections during pregnancy are treated.

"Yeast infections are particularly common during pregnancy," Dr. Hall said. "This study brings into question the long held belief by obstetricians that fluconazole should not be used in pregnancy due to its category D classification depending on usage."

Pregnancy Category D refers to medications for which there is positive evidence of risk to an unborn baby based on data about negative side effects of the medication on the baby.

"Obstetricians historically have been very conservative as it relates to medications recommended during pregnancy," Dr. Hall said.

"Given that there are other options for the treatment of yeast in pregnancy, although admittedly less convenient creams, I would be hesitant to suggest a change to the more convenient pill form of fluconazole based on this one study," he said.

This study was published August 28 in the New England Journal of Medicine.

The research was funded by the Danish Medical Council. The authors reported no potential conflicts of interest.