Diflucan Pregnancy Risk for Birth Defects Evaluated in New Study

A new study that examined the potential pregnancy side effects of Diflucan indicates that the antifungal drug may be related to an increased risk of congenital heart defects in children, but failed to find evidence of a significantly increased risk of birth defects overall.

Danish researchers published their findings this week in the New England Journal of Medicine (NEJM), in a study designed to evaluate whether low doses of the Pfizer medication carry the same risk of birth defects that have been seen in case reports involving long-term, high-dose treatments of Diflucan.

Diflucan (fluconazole) is a prescription drug introduced by Pfizer used to treat yeast infections of the vagina, mouth, esophagus and other organs. It is also used to treat some kinds of meningitis and used as a yeast infection preventative in patients being treated with chemotherapy or radiation therapy before receiving a bone marrow transplant.

In recent years, case reports have suggested that Diflucan side effects cause a pattern of birth defects when high-doses of the medication are used to treat severe fungal infections during pregnancy.

In this latest study, researchers isolated those birth defects into 15 specific types and conducted a registry-based cohort study of liveborn infants in Denmark, correlating data on first-trimester exposure to Diflucan and the rate of birth defects.

Researchers determined that Diflucan exposure was not associated with an overall increased risk of birth defects. Of the 15 different types identified in earlier studies, there was only a significantly increased risk of one; tetralogy of Fallot. The congenital heart defect occurred in one out of 1,000 cases of first-trimester Diflucan exposure, compared to 3 out of every 10,000 occurrences in other pregnancies.

Tetralogy of Fallot involves three to four cyanotic heart abnormalities that result in low oxygenation of the blood as oxygenated and deoxygenated blood is mixed in the left ventrical of the heart. It is the most common cause of what is known as blue baby syndrome.

In August 2011, the FDA issued a drug safety communication about the potential Diflucan pregnancy risks, warning that the agency was changing high doses of Diflucan from a Category C to a Category D pregnancy drug, meaning that there was positive human evidence of a risk of birth defects. The agency did not change the category for single, low-dose uses, but high doses were associated with a number of rare and distinct birth defects and congenital anomalies.

Case studies have linked Diflucan to birth defects when taken in the first trimester, at time when many woman do not even know they are pregnant. According to the FDA, birth defects seen in infants exposed to long-term, high-doses of Diflucan during the first trimester included abnormal head, skull and face defects, cleft palate, cleft lip, bowing of the thigh bones, thin ribs, long bones, muscle weakness, joint deformities and congenital heart disease at birth.