The U.S. Food and Drug Administration issued a warning September 28, 2005, to pregnant women taking Paxil that they may be twice as likely as other women to bear children with birth defects. A study sponsored by Paxil’s manufacturer, GlaxoSmithKline, suggests that the children of women taking Paxil, especially during the first trimester of their pregnancy, were twice as likely to have birth defects. The prevalence of birth defects in this group was 4 percent, or 43.6% per 1000 births.

The most common birth defect suffered by children born to women taking Paxil were ventricular septal defects, where one or more holes are present in the muscular wall separating the right and left ventricles of the heart. The overall rate of heart birth defects in the general population is about 1 percent.

GlaxoSmithKline has said it will send a letter to physicians alerting them to their findings. Paxil already has a pregnancy precaution, belonging to the Category C of prescription drug warnings, meaning that comprehensive studies evaluating the drug’s effect on unborn fetuses have not been done. Citing another survey of births, GSK says it does not note a comparable increase among users of other anti-depressants, but will not admit a causal link between their drug and birth defects.

Source: “Study hints at Paxil tie to birth defects,” Associated Press, September 27, 2005; Amanda Gardner, “New Warning Issued on Paxil,” HealthDay News, September 28, 2005.