Mirtazapine not tied to birth defects risk

By David Douglas

NEW YORK (Reuters Health) - Preliminary indications are that women taking the antidepressant mirtazapine (brand name, Remeron) during pregnancy do not increase the risk of having a baby with birth defects.

However, researchers noted a tendency toward higher rates of preterm birth and miscarriages with the use of mirtazapine.

As Adrienne R. Einarson told Reuters Health, "This is the first study documenting pregnancy outcomes of women who took mirtazapine during pregnancy. From this limited sample size it would appear that mirtazapine does not increase the risk for major malformations."

Einarson, at the Hospital for Sick Children, Toronto and colleagues studied three groups of 104 pregnant women; one group had taken mirtazapine for depression while another group took some other antidepressant, and a third group had been treated with other types of medication.

There were 77 live births in the mirtazapine group, 83 in the other antidepressant group and 92 in the third group, according to the report, published in the Journal of Clinical Psychiatry.

In the mirtazapine group, there was one stillbirth, 20 miscarriages, and six therapeutic abortions. Ninety-five percent of the women in this group took mirtazapine during the first trimester. Only 25 percent continued throughout pregnancy.

The rate of births occurring before 37 weeks was significantly higher in the mirtazapine group (10 percent) than the third group (2 percent). It was also elevated in the other antidepressant group (7 percent).

There were two major malformations in the mirtazapine group, one in the other antidepressant group and two in the non-antidepressant group.

Einarson pointed out that "as in previous studies on antidepressants in pregnancy, there were higher rates of miscarriages in both the mirtazapine group and the comparison group of women taking other antidepressants, than the other comparison group of women who were not."

However, she concluded, this difference was not significant from a statistical standpoint.

SOURCE: Journal of Clinical Psychiatry, August 2006.