January 7, 2013 — According to a new study of data from the National Birth Defects Prevention Study, women who take the antidepressant medication Effexor (venlafaxine) during pregnancy were more likely to have a baby with a birth defect.
The study is important because so few studies have investigated the link between antidepressants in the SNRI (“serotonin norepinephrine reuptake inhibitor”) class and birth defects. Several studies have examined the associations between SSRIs (“selective serotonin reuptake inhibitor”) antidepressants during pregnancy, and they have found higher risks of defects affecting the heart, abdomen, cranium, and more.
The researchers used data from the National Birth Defects Prevention Study, which is an ongoing database of birth defects and potential risk factors, including medications that were taken during pregnancy. The researchers investigated the use of Effexor during pregnancy from 1997 to 2007. They assessed 24 groups of birth defects, and found statistically significant associations between Effexor and anencephaly, cleft palate, gastroschisis, some heart defects, and more.
- Anencephaly occurs when much of the baby’s brain and skull fail to develop.
- Septal heart defects occur when the septal wall between heart chambers has holes, which may require heart surgery shortly after birth.
- Coarctation of the aorta occurs when the aorta is more narrow than usual. The aorta typically carries oxygen-rich blood from the heart into the body.
- Cleft palate is a oral-facial birth defect that occurs when there is a split in the roof of the mouth, which may extend into the gums, lip, and throat.
- Gastroschisis is an abdominal defect that occurs when the intestines protrude outside the body through a hernia in the abdominal wall.
The researchers hypothesized that the link between Effexor and birth defects could be explained by the effect of the medication on serotonin, which is a neurotransmitter involved in early fetal development. The researchers wrote, “If venlafaxine is taken during early pregnancy and interferes with these embryologic signaling pathways, it is plausible that venlafaxine could affect craniofacial and cardiac development. This is consistent with out findings of association with septal heart defects … and cleft palate.”
The researchers concluded with the following warning:
“Our data suggest that maternal periconceptional use of venlafaxine might be associated with certain birth defects, specifically anencephaly, cleft palate, gastroschisis, and some heart defects, such as ASD secundum or ASD not otherwise specified, and coarctation of the aorta.”