The study was published in Birth Defects Research (Part A) (2012) and involved studying venlafaxine (the generic name of Effexor) to determine if use of the antidepressant during pregnancy was associated with specific birth defects. Data was obtained from the National Birth Defects Prevention Study and included mothers with infants who had one of 30 birth defects compared with mothers with infants without birth defects. Researchers included anyone who took venlafaxine from one month prior to pregnancy through the third month of pregnancy as being “exposed” to the drug.
Researchers noted that although venlafaxine is an SNRI, due to the lower numbers of users, it is often grouped with a similar class of drugs, selective serotonin reuptake inhibitors (SSRIs), although SNRI medications affect levels of both serotonin and norepinephrine in the patient’s system. Studies that did examine SNRIs separately from SSRIs did not find a significant difference in the rate of birth defects between the two. Meanwhile, studies examining the risk of birth defects associated with SSRI medications have produced mixed results, with some suggesting an association and others suggesting no association.
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Still, they theorized that it is possible venlafaxine affects craniofacial and cardiac development, resulting in the types of birth defects seen in the study. Researchers concluded by noting that additional studies are needed to confirm the results of their study.