SSRIs are not major teratogens when taken in first trimester

As a group, selective serotonin reuptake inhibitors (SSRIs) taken during the first trimester of pregnancy do not increase the risk of most birth defects, according to two studies published in the June 28 issue of the New England Journal of Medicine. There may be possible exceptions for particular SSRIs and some rare birth defects, but the absolute risks are small.

In the first study, Carol Louik, ScD, from the Slone Epidemiology Center at Boston University, and colleagues examined the association between maternal SSRI use during the first trimester and birth defects in 9,849 infants with birth defects and 5,860 infants without birth defects. The investigators found that there were no significant increases in the risks of craniosynostosis, omphalocele, or heart defects associated with SSRIs as a group, although individual SSRIs increased the risk of certain rare birth defects but with a low absolute risk.

In the second study, Jennita Reefhuis, PhD, from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues examined the association between maternal SSRI use during the first trimester and birth defects in 9,622 infants with major birth defects and 4,092 infants without birth defects. The researchers found no increased risk of most birth defects associated with SSRIs as a group, apart from an increased risk of anencephaly, craniosynostosis, and omphalocele, though the absolute risks were small, the authors conclude.

Louik C, Lin AE, Werler MM, et al. First-trimester use of selective serotonin-reuptake inhibitors and the risk of birth defects. N Engl J Med. 2007;356:2675-2683.