A meta-analysis of previous studies claim that expectant mothers taking the antidepressant paroxetine (Paxil, Seroxat) during the early stages of their of pregnancy can result to birth defects. Result is particularly high during the first trimester.

Even if the risk for congenital anomaly remains small (1 to 3 percent) among mother taking paroxetine amid the entire pregnancy, this latest systematic review reveals its prevalence rate could be higher during the first trimester, with an increased risk of 23 and 28 percent for congenital malformations and heart defects, respectively.

Study author Anick Berard of the Research Center, Centre Hospitalier Universitaire Sainte-Justine, and colleagues collated and analyzed 23 published studies from EMBASE and MEDLINE databases between 1966 and 2015, which included from 500 to over 900,000 participants from the United States, Canada, Europe, Australia and Israel that met the inclusion criteria.

In their review, they suggested that during the first trimester, paroxetine has the potential to block fetal reuptake of serotonin, an effect similar to all selective serotonin reuptake inhibitors (SSRIs). According to Dr. Berard, during embryogenesis, serotonin is an important agent for organ development such as the heart, musculoskeletal system and CNS. Since SSRIs restrict serotonin during this critical period, birth defects are likely to occur, particularly heart defects.

The study did not confirm the causal relationship between taking paroxetine and birth defects, though. However, Dr. Berard highly believes that the latest finding is of benefit to pregnant women, taking into consideration that the drug is a commonly prescribed medication and an estimated one-fifth of women in their child-bearing age manifest signs of depression.

Since the birth defect rate of some studies was small, authors pointed out that it still needs further investigations. The results reveal insufficient proof of severity of depression, and they are also taking into account possible factors that might have contributed to increase the risk.