SSRIs Taken During Pregnancy Linked to Increased Risk for Birth Defects

A new study urges women to consider the dangers of commonly prescribed antidepressants, which may increase birth defect risks. REUTERS/Carlos Barria

For some time, doctors have suspected that serotonin reuptake inhibitors (SSRIs), a commonly prescribed class of antidepressant drugs, may be harmful to a developing fetus and increase the risk for birth defects. However, studies on the topic have provided mixed results, especially when it comes to distinguishing the level of risk among the various medications in this class.

A new study published Wednesday in BMJ provides further proof that SSRIs are likely to be cause of birth defects, but the risk may still be relatively small, at least for some of types of this drug.

The large-scale study looked at data from the U.S. National Birth Defects Prevention Study, which involved nearly 18,000 mothers of infants with birth defects and nearly 10,000 mothers who had infants without birth defects. All births took place between 1997 and 2009. Women included in the analysis had used an SSRI at least a month before conception and throughout pregnancy.

The researchers found that birth defects were two to 3.5 times more likely to occur in infants that were born from mothers who had taken certain SSRIs, compared with mothers who hadn't taken these drugs. Paroxetine and fluoxetine were drugs in the class that demonstrated the strongest association with birth defects, especially when taken early in the pregnancy. The most common complications included heart wall and abdominal wall defects, as well as brain and skull malformation. Sertraline, the SSRI prescribed to 40 percent of women in the study, was linked to the lowest rates for birth defects.

However, the authors stress that while their findings do agree with previous reports about the dangers of SSRI use during pregnancy, their statistical analysis indicates the risk level is still relatively low. The absolute risks for brain and skull malformation in infants of women who took paroxetine early in pregnancy would increase from two per 10,000 births to seven per 10,000 births. The risk for heart defects could increase from 10 per 10,000 births to 24 per 10,000 births.

"Continued scrutiny of the association between SSRIs and birth defects is warranted, and additional studies of specific SSRI treatments during pregnancy and birth defects are needed to enable women and their health care providers to make more informed decisions about treatment," the researchers write in their study's conclusion. "Meanwhile, the current analysis can help guide health care providers and women to the safest options for treatment during early pregnancy to minimize the risk of major birth defects, while providing adequate treatment of maternal depression."