Does Pristiq Cause Birth Defects?

November 20, 2012 — It is possible that using the antidepressant medication Pristiq (desvenlafaxine) during pregnancy increases the risk of having a baby with a birth defect.

However, no well-controlled studies have been conducted, because it would be unethical to randomly assign pregnant women Pristiq or a placebo and monitor their babies for birth defects. Although “cause-and-effect” cannot be conclusively established, experts have found evidence linking Pristiq to birth defects in the first trimester and third trimester of pregnancy.

According to the U.S. Food and Drug Administration (FDA), Pristiq is a “Pregnancy Category C” drug. Although there may be an increased risk of birth defects, doctors can still prescribe Pristiq if the benefits outweigh any risks. Relapsing into depression can also adversely influence fetal development, and this risk must be carefully weighed against the risk of birth defects.

One of the most serious and well-established risks is fetal drug withdrawal at birth, which occurs in about 30% of newborns exposed to an antidepressant in the third trimester. The side effect information on Pristiq’s label includes this risk, and a warning that babies may require prolonged hospitalization, tube feeding, or respiratory support. These effects are consistent with a “direct toxic effect” of Pristiq in a developing baby.

Other studies have raised concerns about using antidepressants during the first trimester of pregnancy. One study, published in December 2011 in Reproductive Toxicology, warned that serotonin is very important in the first few weeks of fetal development — before most women are even aware of pregnancy. During this time, serotonin acts as a signaling molecule in cell proliferation, differentiation, migration, and death. According to the researchers, it is “biologically plausible” that a medication that disrupts the fetal serotonin system could cause a life-threatening birth defect.