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Do SSRIs Cause Birth Defects?

Two large case-control studies indicate a few very small increases in risks for particular defects.

Earlier studies reported that use of selective serotonin reuptake inhibitors (SSRIs) —especially paroxetine — during early pregnancy increases the incidence of cardiovascular birth defects markedly. Now, two large ongoing case-control studies challenge these findings.

Investigators from the U.S. and Canada identified 9622 infants with major birth defects, and 4092 controls without such defects, born between 1997 and 2002. No significant association was found between SSRI use in early pregnancy and congenital heart defects. However, there were small absolute increases in risks for anencephaly, craniosynostosis, and omphalocele with SSRI use, and all these risks — as well as the risk for ventricular outflow tract lesions — were increased most with paroxetine.

In a second study, funded in part by the manufacturer of paroxetine, 9849 infants with birth defects were compared with 5860 control infants born in five centers in the U.S. and Canada between 1993 and 2005. Use of SSRIs in early pregnancy was not associated with heart defects in general, but there was an increased risk for right ventricular outflow tract lesions with paroxetine and an increased risk for septal defects with sertraline. No evidence of increased risk was found for any other birth defects with paroxetine.

Comment: As an editorialist notes, these studies dispel the belief that SSRIs are major causes of birth defects. The absolute risk for right ventricular outflow tract lesions in the infant of a mother who uses paroxetine during pregnancy is likely less than 1%, and the risk for any congenital heart defect is unlikely to exceed 2%. These small risks must be weighed against the risks associated with discontinuing an SSRI during pregnancy.

— Robert W. Rebar, MD

Published in Journal Watch General Medicine June 27, 2007

Citation(s):

Alwan S et al. Use of selective serotonin-reuptake inhibitors in pregnancy and the risk of birth defects. N Engl J Med 2007 Jun 28; 356:2684-92.

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Louik C et al. First-trimester use of selective serotonin-reuptake inhibitors and the risk of birth defects. N Engl J Med 2007 Jun 28; 356:2675-83.

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Greene MF. Teratogenicity of SSRIs — Serious concern or much ado about little? N Engl J Med 2007 Jun 28; 356:2732-3.

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