Antidepressants, Birth Defects and a Broken System

The headlines from the last few days were scary:

“Link Between Some Antidepressants and Birth Defects is Confirmed” The Washington Post

“Some Antidepressants May Pose Increased Risk of Birth Defects” NPR

“CDC: Some Antidepressants, but Not Others, Linked with Birth Defects” USA Today

“Pfizer ‘Hid Link’ Between Anti-Depressants and Birth Defects” Center for Research on Globalization

“SSRI Antidepressants Linked to Birth Defects” Nursing in Practice

Prozac Was First

Prozac (fluoxetine) was the first of a new type of antidepressant (SSRI) that came on the market starting in 1987, roughly 28 years ago. The success of Prozac led to similar antidepressants including Paxil (paroxetine) and Zoloft (sertraline). Millions have taken these drugs over the last three decades and we have gradually learned more about side effects over that time span.

This week the big news from a CDC study published in the BMJ reveals apparent differences among antidepressants when it comes to birth defects. In the data that CDC analyzed, women taking Prozac or Paxil but not those taking other antidepressants were more likely to have babies with defects affecting their hearts or heads.

In the study, data on nearly 18,000 women whose babies had birth defects were compared to data on almost 10,000 women whose infants had no birth defects. Out of all these women, 1,285 had taken an SSRI antidepressant during the first trimester of pregnancy, when a fetus is most vulnerable.

What Took So Long?

This research was based on analysis of information collected between 1997 and 2009 at 10 different medical centers. Back in December, 2005, there was a red flag that paroxetine might be linked to heart defects. It is unethical to expose a pregnant woman and her fetus to a potentially harmful compound, so the scientists needed to look for information on women who were taking antidepressants anyway as part of their usual care. Then they needed to get information on women who were comparable in other respects but not on antidepressants. It took quite a while to find the right data set.

The risk of birth defects such as missing part of the brain rises from 2 per 10,000 for American women in general to 7 in 10,000 for women taking Paxil. This is a large relative increase, but the overall risk is still extremely low. Nevertheless, it is disappointing that it took nearly three decades to discover this serious complication.

This delay of nearly three decades between the time the drugs appeared and the discovery of a link to birth defects demonstrates that there is not a good system to determine whether a medication is safe during pregnancy. CDC and FDA should work together to figure out a better way. American women deserve it.

What Should Women Do?

The American Psychiatric Association collaborated with the American College of Obstetricians and Gynecologists in 2009 on guidelines for treating depression during pregnancy. They suggest that women who have had little difficulty with symptoms of depression recently might be weaned off their antidepressant. Others, especially those whose depression is severe, may need to continue drug treatment throughout pregnancy. The investigators urge women to discuss this topic with their health care providers before becoming pregnant, if possible.

Now that the data show differences among antidepressants, psychiatrists may be able to switch a woman to a medication that would be less likely to pose a risk of birth defects. No woman should stop taking an antidepressant suddenly, as this can lead to terrible withdrawal symptoms.

BMJ, July 8, 2015