Will We Ever Know for Sure if Paxil Causes Paxil Birth Defects?

Toronto, OntarioThe debate over Paxil side effects as they relate to infants born with heart defects continues to be hotly contested—especially given the need for some women to remain on antidepressants on a consistent basis for depression. So do you stop an antidepressant like Paxil during pregnancy and risk harming the mother? Or do you continue and risk Paxil birth defects?

As recently as this past August, Motherisk, a department of women's health at the Hospital for Sick Children in Toronto, concluded "the evidence that paroxetine (Paxil) increases the rate of cardiac malformations above the population baseline risk of one out of 100 pregnancies just does not exist."

This, in spite of the Paxil lawsuit where Paxil manufacturer GlaxoSmithKline (Glaxo) was required to pay a $2.5 million settlement to the family of a child born with a heart defect. The child's mother took Paxil during the first trimester of her pregnancy.

There is little doubt that the issue has been well studied. However, conclusions vary. Motherisk noted a 2005 study posted by Glaxo on its Web site that suggested a two percent risk of congenital malformations, compared with one percent in the control group. A separate study in Sweden arrived at similar findings.

However, Motherisk conducted its own prospective, comparative cohort study with data from teratogen information services globally. Analyzing the outcomes of 1,170 infants from eight teratogen services found the rate of heart defects in the Paxil group and that in the control group was equal at 0.7 percent.

Motherisk also noted on its Web site, in a posting from August, that two additional studies out this year on Paxil defects both found a marginal increase in heart defects associated with paroxetine (Paxil). And yet the odds ratio was below two—which represents a marginal increase in risk at best.

Similar findings were published in March of this year by Wurst et al, together with two dissenting views…

"The scientific evidence does not support the conclusion that paroxetine causes cardiovascular defects," said one.

"Evidence-based literature shows consistent epidemiologic evidence that paroxetine use during pregnancy increases the risk of cardiac malformations in newborns," said the other.

Motherisk concludes that heart defects are relatively commonplace, with about one out of 100 babies born with a heart defect regardless of exposure. "Accumulated evidence from different types of studies does not suggest that paroxetine is associated with an increased risk of heart defects."

Thus, does using Paxil during pregnancy still run the risk for Paxil heart defects? The jury is apparently still out…