Women taking a selective serotonin reuptake inhibitor (SSRI) antidepressant were more likely to have a miscarriage than similar women who were not taking antidepressants, according to a study published May 31 in the Canadian Medical Association Journal and reported by CBC News.

Up to 15 percent of pregnant women experience depression, and nearly 4 percent will use an antidepressant during the first trimester. Thus far, there have been hints that the medications might increase the risk of a spontaneous abortion (miscarriage), but results have been inconclusive.

To determine whether there is, in fact, a link between antidepressants and miscarriages, Anick Bérard, PhD, of the University of Montreal, and her colleagues examined the pregnancy registry in the province of Montreal between 1997 and 2003. Of the 5,124 miscarriages on record, each was matched with 10 similar pregnant women who did not have a miscarriage.

Bérard and her colleagues found that women who filled at least one prescription for antidepressants during the first trimester of pregnancy were nearly twice as likely to have a miscarriage as women who did not fill a prescription for antidepressants. Moreover, women taking Paxil (paroxetine) or Effexor (venlafaxine), and women taking more than one antidepressant, appeared to have the highest likelihood for a miscarriage. None of this definitively proves that antidepressants cause miscarriages. Other factors may explain why the miscarriage rate was higher among women taking antidepressants.

Nevertheless, the authors do state that doctors should discuss these results with pregnant women who are struggling with depression, concluding: “In light of our results, physicians who have patients of childbearing age taking antidepressants or have pregnant patients who require antidepressant therapy early in pregnancy may wish to discuss the risks and benefits with them.”

An accompanying editorial by Adrienne Einarson, a registered nurse, urges that women not discount the benefits of antidepressant medication or overstate the study’s results, saying, “Despite all the limitations, there does seem to be a very, very slight risk, but not enough to make any difference when the woman needs to be treated for depression in pregnancy.”