Taking antidepressants during pregnancy increases the risk of spontaneous abortions by about two-thirds, Canadian researchers reported Monday. The increased risk was greatest with the family of drugs known as selective serotonin reuptake inhibitors (SSRIs), especially paroxetine and venlafaxine, and when more than one family of drugs were used.
Depression in women is most common during the child-bearing years, and estimates suggest that as many as 15% of pregnant women suffer from it. Because of fears about the effects of drugs, particularly psychiatric drugs, during pregnancy, only about 3.7% of women use them during the first trimester. Most studies looking at the use of antidepressants during pregnancy have focused on their effects on the fetus. Small studies of their effects on abortion have produced inconsistent results. Expecting mothers cannot routinely stop using the drugs, however, because that also presents risks to both the mother and the fetus.
Producing a controlled clinical trial examining the effects of the drugs is virtually impossible because few women would be willing to participate, experts said. The only way to get at the data is to examine it retrospectively.
In the new study, Dr. Anick Berard, director of the University of Montreal's Research Unit on Medications and Pregnancy at University Hospital Center Sainte-Justine used information from the Quebec Pregnancy Registry to identify 5,124 women who had a spontaneous abortions between 1998 and 2003 -- before warnings about the risks of the drugs became more common -- and compared them with about 10 times that many carefully matched women who did not have abortions. A separate database provided information about prescriptions the women had filled.
The researchers reported in the Canadian Medical Assn. Journal that 5.5% of the women who had spontaneous abortions had taken antidepressants, compared with 2.7% of those who did not have a spontaneous abortion. Controlling for other factors, that amounted to a 68% increase in risk. The biggest effects were found with paroxetine (brand names Paxil and Seroxat) and venlafaxine (Effexor) or when combinations of drugs from different families were used.
In a commentary in the same journal, Adrienne Einarson, a registered nurse who is assistant director of the Motherisk Program at the Hospital for Sick Children in Toronto, noted that the study had many deficiencies: many spontaneous abortions are not reported to doctors, the researchers did not know if the women actually took the drugs and they did not monitor the extent of the depression. Nonetheless, the increased risk in the study was about the same as that found by Motherisk (a teratology information service) in an earlier study, she said.
The bottom line, it appears, is that the drugs do slightly increase the risk of a spontaneous abortion, but there are so many other factors leading to abortions that the overall risk is probably relatively small.
-- Thomas H. Maugh II