Antidepressants and Spontaneous Abortion: Classifying the Risk

Many women experience bouts of depression during pregnancy. Likewise, in the weeks following birth, a condition known as postpartum depression is not uncommon. In the past, doctors had little hesitation in prescribing antidepressant medications to pregnant women. Attending physicians believed that moderate or major depression put both mother and child at risk for a variety of complications. Since 2004, several public health agencies, including the U.S. Food and Drug Administration, have published guidelines that caution against the prescription of antidepressants to pregnant women. Numerous studies have implicated antidepressant medications in both spontaneous abortions and birth defects. However, gaps in the research have remained. For instance, doctors had no data on which antidepressants posed relatively greater or lesser risk to pregnant women, so risk-benefit analyses were impossible. A review of data contained in the Quebec Pregnancy Registry aimed to fill some of these information gaps.

The study authors identified 5,124 cases of spontaneous abortion in the database. For the control group, they selected 51,240 women of matching ages and circumstances. Every attempt was made to account for and eliminate confounding variables, those factors that are notorious for skewing and distorting result sets. Overall, the data indicated that pregnant women who took any form of antidepressant had a 68% greater chance of experiencing a spontaneous abortion than women who did not take an antidepressant. The risk was most obvious among the selective serotonin reuptake inhibitors, one of the newest and most commonly prescribed classes of antidepressants. Researchers also found that taking more than one kind of antidepressant during pregnancy doubled the odds of a spontaneous abortion. When the results were parsed to the level of specific drugs, the results were even more informative.

Two drugs stood out in terms of their observed risk to the unborn: Paxil (paroxetine) and Effexor (venlafaxine). These drugs showed the greatest significance in terms of increased risk of spontaneous abortion when compared with the unmedicated control group. As far as individual drugs are concerned, no other one demonstrated a statistically significant risk for spontaneous abortion. Only when the drugs were grouped together did the risk become apparent and significant.

The Quebec Pregnancy Registry study is an important first step in quantifying the risks entailed by taking antidepressant drugs during pregnancy. The study authors were quick to point out that although similar previous research was inconclusive or contradictory, the enormous sample size of the pregnancy registry offers a lot of statistical power. Whereas earlier studies might have enrolled dozens or hundreds of women, this analysis included tens of thousands. Furthermore, the database provided the ability to recognize and eliminate confounding variables. In the end, this study provides more discrete information for attending physicians, so they can make informed decisions about the best course of action for pregnant women under their care.

Nakhai-Pour, H. R., Broy, P., Berard, A. (2010). Use of antidepressants during pregnancy and the risk of spontaneous abortion. Canadian Medical Association Journal, 182(10), 1031-1037.

© Copyright 2011 by James Pendleton. All Rights Reserved. Permission to publish granted to

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