(HealthDay News) – Commonly used low doses of fluconazole during pregnancy do not increase the risk of most birth defects but may confer an increased risk of tetralogy of Fallot, according to a study published in the Aug. 29 issue of the New England Journal of Medicine.

Noting that long-term, high-dose fluconazole during pregnancy has been associated with birth defects, Ditte Mølgaard-Nielsen, MSc, and colleagues from the Statens Serum Institut in Copenhagen, Denmark, analyzed the prevalence of birth defects among approximately one million liveborn infants in Denmark based on exposure to lower doses of oral fluconazole during pregnancy.

The researchers found that, of fluconazole-exposed pregnancies, 56% were exposed to 150mg fluconazole and 31% were exposed to 300mg fluconazole. There was no significant increase in birth defects among women exposed to fluconazole during pregnancy vs. those not exposed (prevalence, 2.86% vs. 2.6%; adjusted prevalence odds ratio, 1.06). There was also no significant increase in the risk of 14 of 15 types of birth defects that had been previously associated with exposure to fluconazole during pregnancy, with the exception of tetralogy of Fallot (prevalence, 0.1% vs. 0.03%; adjusted prevalence odds ratio, 3.16).

“Oral fluconazole was not associated with a significantly increased risk of birth defects overall or of 14 of the 15 specific birth defects of previous concern,” Mølgaard-Nielsen and colleagues conclude. “Fluconazole exposure may confer an increased risk of tetralogy of Fallot.”

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