Selective serotonin reuptake inhibitors – also known as SSRIs – are the most common drugs for treating depression in pregnant women. One particular drug in that class called paroxetine – branded as Paxil in the US – was previously considered safe for use during pregnancy, but a new study reveals increased risks of birth defects for offspring.

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The latest study suggests use of paroxetine during early pregnancy is linked to increased risk of cardiac malformations in newborns.

January is Birth Defects Prevention Month, and as such, the medical community is making every effort to inform health care professionals and patients about steps that can be taken to prevent birth defects in newborns.

The latest study, led by Prof. Anick Bérard, of CHU Sainte-Justine and the University of Montreal in Canada, is published in the British Journal of Clinical Pharmacology.

But this is not the first time antidepressant use in pregnancy has been linked to risks in offspring. A recent study published in JAMA Pediatrics demonstrated a link between SSRI use in pregnancy and increased risk of autism in children.

For their latest research, Prof. Bérard and colleagues focused on paroxetine, which is used to treat depression, panic disorder, social anxiety disorder, obsessive-compulsive disorder (OCD), generalized anxiety disorder and posttraumatic stress disorder (PTSD).

A member of the SSRI class, paroxetine works by increasing the amount of serotonin, which is a substance in the brain that helps with maintaining mental balance.

According to the researchers, up to one fifth of women who are of childbearing age experience mild to moderate depression. Furthermore, in recent years, prescriptions for antidepressants during pregnancy have increased.

Fast facts about SSRIs
  • SSRIs are the most commonly prescribed class of antidepressants
  • They work by blocking the reabsorption of serotonin in the brain
  • By changing the balance of serotonin, SSRIs help brain cells send and receive chemical messages, boosting mood.

Learn more about antidepressants

Although paroxetine was considered safe for use during pregnancy up until 2005, a small – unpublished – study led by the manufacturer showed an increased risk of cardiac malformations in babies exposed to the drug before birth.

However, further studies that employed varying study designs in Europe and North America yielded conflicting results; still, a trend toward an increased risk emerged.

In order to provide a thorough analysis of the effects of paroxetine on newborns, the researchers carried out a literature review and meta-analysis of all pertinent studies published between 1966-2015. Of these studies, 23 emerged that were eligible.

Results revealed that compared with no paroxetine use, first-trimester use of the drug was linked with a 23% increased risk of any major congenital malformations and a 28% increased risk of major cardiac malformations in newborns.

“Given that the benefits of antidepressants overall, and selective serotonin reuptake inhibitors including paroxetine specifically, during pregnancy is questionable at best, any increase in risk – small or large – is too high,” says Prof. Bérard.

She and her team note that the baseline risk of major malformations is 3% and of cardiac malformations is just 1%.

However, they add that any increase in risk is significant, particularly considering that the benefit of using SSRIs during pregnancy is questionable, given that changes in metabolism can cause the drugs to be cleared from the body at a faster rate.

Commenting further, Prof. Bérard says:

”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. Therefore, planning of pregnancy is essential, and valid treatment options such as psychotherapy or exercise regimens are warranted in this special population.”

The researchers conclude their study by noting that the increase in risk “is not dependent on the study method or population.”

In August of last year, Medical News Today reported on another study that suggested SSRI use in pregnancy is linked to reduced risk of preterm birth but increased risk of neonatal problems.