Using the antidepressant paroxetine during the first trimester of pregnancy may increase the risk of major congenital and cardiac malformations in newborns. That’s according to a new analysis of relevant studies from 1966 to 2015 published in the British Journal of Clinical Pharmacology.

Paroxetine is a selective serotonin reuptake inhibitor (SSRI), and up until 2005 it was considered safe for use during pregnancy. However, an unpublished study by the manufacturer suggested an increased risk of cardiac malformations in infants exposed to paroxetine before birth. Various follow up studies have thrown up some contradictory results, however, the trend has shown a general increase in risk.

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In this latest analysis, the team of researchers from CHU Sainte-Justine and the University of Montreal found a 23% increased risk of major congenital malformations and a 28% risk of major cardiac malformations in infants associated with first trimester paroxetine use, compared to those with no use of paroxetine.

During pregnancy natural changes in metabolism cause SSRIs to be cleared from the body much quicker, making the benefits of taking such treatments debatable. “Indeed, the risk/benefit ratio suggests non-use in women with mild to moderately depressive symptoms, which is 85% of pregnant women with depressive symptoms,” said Professor Anick Bérard, PhD, lead author of the analysis. “Therefore, planning of pregnancy is essential, and valid treatment options such as psychotherapy or exercise regimens are warranted in this special population.”

For more information view the current issue of the British Journal of Clinical Pharmacology.