Paxil, a popular antidepressant made by GlaxoSmithKline, has been linked to serious birth defects in children whose mothers used Paxil during the first months of pregnancy. Most Pail birth defects involve septal defects of the heart, which are holes between the heart's two main pumping chambers. In some studies, women who took Paxil during the first three months of pregnancy were about one and a half to two times as likely to have a baby with a heart defect as women who received other antidepressants or women in the general population. In 2005 GlaxoSmithKline modified the drug's labeling twice to reflect the birth defect risk, and the Food & Drug Administration place Paxil in a new pregnancy risk Category D - meaning there was now positive evidence that Paxil use put a developing fetus at risk of birth defects.