SSRI antidepressants and birth defects

(1) Between 20% and 30% of newborns exposed to selective serotonin reuptake inhibitor antidepressants (SSRIs) towards the end of gestation have disorders such as agitation, abnormal muscle tone and suction, seizures and hyponatraemia. (2) Worrisome data concerning a possible teratogenic effect were published in late 2005. (3) In a Danish cohort including 1054 pregnant women, the estimated relative risk of all congenital malformations, compared with the general population, among the offspring of women who received a prescription for an SSRI was 1.4 (95% CI 1.1-1.9), and the relative risk of cardiac malformations was 1.6 (95% CI 1.0-2.6). (4) An American retrospective study compared the newborns of women who were prescribed paroxetine during the first trimester of pregnancy with all newborns exposed to other antidepressants: 4% of newborns exposed to paroxetine had malformations (2% had cardiac malformations). The estimated relative risk for all congenital malformations was 2.20 (95% CI 1.34-3.63), and the estimated relative risk of cardiovascular malformations was 2.08 (95% CI 1.03-4.23). (5) Analysis of a Swedish birth register provided an estimated relative risk of cardiac malformations associated with paroxetine of 2.22 (95% CI 1.39-3.55) compared with the general population. (6) Another American study showed a global increase in the risk of malformations with paroxetine compared with all antidepressants. The risk of cardiovascular malformations was not significantly increased. (7) In a case-control study based on an American register of birth defects, the estimated relative risk of omphalocele was 3.0 with all SSRIs (95% CI 1.4 to 6.1), and the estimated relative risk of craniosynostosis was 1.8 (95% CI 1.0-3.2). (8) In practice, all SSRIs have been implicated in a possible increase in the risk of congenital malformations, but the most worrisome evidence concerns paroxetine. This potential risk implies that the justification for paroxetine treatment in pregnant women should be carefully weighed; this means double-checking the diagnosis, the potential benefits and adverse effects, and possible alternatives.