Advertisement  

July 22, 2015
Some SSRIs in Early Pregnancy Increase Birth Defect Risks

Atlanta—A new analysis seeking to resolve confusion from conflicting results in previous studies now suggests that taking selective serotonin reuptake inhibitors (SSRIs) in early pregnancy might be associated with a slight increase in risk of birth defects.

The British Medical Journal report, which combines results from independent published analyses with data from a multicenter, population-based case-control study of birth defects, emphasizes that the absolute risk for those birth defects is low and calls for more studies “to enable women and their healthcare providers to make more informed decisions about treatment.”

The U.S.-Canadian analysis, which was led by researchers from the National Center on Birth Defects and Developmental Disabilities at the national Centers for Disease Control and Prevention, included 17,952 mothers of infants with birth defects and 9,857 mothers of infants without birth defects, born between 1997 and 2009.

“This analysis confirms the need to assess the association between specific SSRIs and specific birth defects rather than combining an entire drug class or heterogeneous group of birth defects,” the researchers emphasize. “Although SSRIs are similar pharmacologically, there are chemical differences, and if any of them do have teratogenic activity, it may be completely unrelated to the inhibition of serotonin receptors. SSRIs also differ pharmacokinetically, and this could account for differences in teratogenic activity, whether or not the mechanism involved inhibition of serotonin receptors.”

For the study, the researchers documented use of the SSRI drugs citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), paroxetine (Paxil), or sertraline (Zoloft) at least once in the period from 1 month before conception through the third month of pregnancy. Women who reported taking antidepressants other than SSRIs or reporting pre-existing diabetes were excluded.

While sertraline was the most commonly used SSRI, none of the five previously reported associations between sertraline and birth defects were confirmed. Study authors called that especially reassuring, because about 40% of women reporting use of an SSRI in early pregnancy were on sertraline.

For nine other previously reported associations between maternal SSRI use and birth defects in infants, findings also failed to be confirmed. Two previously reported birth defects associated with fluoxetine treatment—heart wall defects and irregular skull shape (craniosynostosis)—were identified, however.

In addition, five previously reported birth defects associated with paroxetine treatment were also observed, including heart defects, problems with brain and skull formation (anencephaly), and abdominal wall defects.

While expectant mothers might find some of the data reassuring, study authors point out, the evidence does suggest that some birth defects occur more frequently among the infants of women treated with paroxetine or fluoxetine in early pregnancy.

“Although our analysis strongly supports the validity of the associations that were observed, the increase in the absolute risks, if the associations are causal, is small,” the researchers emphasize, noting that the absolute risks of paroxetine therapy early in pregnancy show an increase in anencephaly risk from 2 per 10,000 to 7 per 10,000, and the risk for one of the heart defects from 10 per 10,000 to 24 per 10,000.

“Continued scrutiny of the association between SSRIs and birth defects is warranted and additional studies of specific SSRI treatments during pregnancy are needed to enable women and their healthcare providers to make more informed decisions about treatment,” the study states, adding, “Meanwhile, the current analysis provides guidance to the safest treatment options during early pregnancy to minimize the risk of major birth defects, while providing adequate treatment of maternal depression.”



Connect With U.S. Pharmacist
USP Google AppUSP Itunes App