The FDA issued a Public Health Advisory today about Paxil (paroxetine), the prescription anti-depressant. The agency has determined that exposure to Paxil in the first trimester of pregnancy may increase the risk of congenital malformations in infants, particularly cardiac malformations.

Preliminary analysis of two unpublished studies bore this conclusion out. In a study using national registry data from Sweden, women who received Paxil in early pregnancy has an approximately two-fold increased risk for birthing an infant with a cardiac defect compared to the regular population. In a separate study of U.S. insurance claims data, infants of women on Paxil had a 1.5 times greater chance for cardiac malformations and a 1.8 times greater chance for congenital malfunctions in general. Paxil is manufactured by drugmaking giant GlaxoSmithKline plc.

The cardiac defects observed in these studies were atrial or ventricular septal defects, conditions in which the wall between the right and left sides of the heart is not completely developed. Septal defects are one of the most common type of congenital malformations. They range from those that are symptomatic and may require surgery to those that are asymptomatic and may resolve on their own.

Source: FDA Release, December 8, 2005.