Other Risk-Factors Blamed for Antidepressant Heart Defects

June 19, 2014 — The New England Journal of Medicine has published a study concluding that pregnant women who use antidepressants during the first trimester are not more likely to have a baby with a heart defect.

Nearly one million women who had given birth were included in the study. They were all on Medicaid without supplementary private insurance. About 64,000 (6.8%) of the women used antidepressants in the first three months of pregnancy.

Researchers found that 72 out of every 10,000 babies who were not exposed to an antidepressant had a heart defect, compared to 90 out of 10,000 babies whose mothers had taken antidepressants. That translates to a 25% increased risk — but those numbers include women who also drink alcohol, smoke, and use other psychotropic medications.

When researchers controlled for those risk-factors, leaving 217,342 women, they found that the risk of heart defects dropped to 12%. After eliminating women with diabetes, high blood pressure, severe depression, and other potential confounders, the risk of heart defects was just 6% — and that number was small enough that it could have been due to chance, leading researchers to conclude that SSRI antidepressants do not cause heart defects.

The findings of the study are unexpected because in 2005, the U.S. Food and Drug Administration (FDA) warned healthcare professionals that Paxil (paroxetine) could increase the risk of heart defects when it was taken during the first trimester. Their concern was based on two epidemiological studies, but it was unclear whether the associations were causal or due to other problems. Other antidepressants, including Zoloft (sertraline), have also been linked to an increased risk of heart defects.

The decision about whether to take an antidepressant during pregnancy is often very difficult. Without treatment, women can relapse into depression and stop taking care of themselves, which could harm a fetus or newborn infant. Although the study is reassuring, it has limitations. Researchers did not look at the rate of miscarriages, for example, which have been linked to antidepressants. Excluding miscarriages might also eliminate data on pregnancies with severe outcomes.