Paxil's manufacturer, GlaxoSmithKline, says it will include the results of the study in the drug's precaution list.
According to the FDA and the company, a retrospective study finds increased numbers of babies born with birth defects to women taking Paxil during the first trimester of pregnancy, compared with women on other antidepressants.
This includes an increase in heart defects, according to a letter from GlaxoSmithKline to health care professionals released Tuesday.
The drug, which goes by the generic name paroxetine, is already classified as a "Category C" drug for pregnant women - meaning comprehensive studies of its effects on a pregnancy have not been conducted.
Based on the study, the company says it has not concluded there exists a definite link between the drug and increased instances of birth defects. GlaxoSmithKline cites another survey of births that it says does not show a comparable increase.
