A team from the Ottawa Health Research Institute, the University of Ottawa, and The Ottawa Hospital has found an increased risk of premature delivery, low birth weight, fetal death, and infant seizures among pregnant women who used a popular class of antidepressants during pregnancy.

The study, published in the April issue of the American Journal of Obstetrics and Gynecology, uses linked maternal / infant prescription and health records to assess the safety of a class of antidepressants known as selective serotonin re-uptake inhibitors (SSRIs). Records were obtained for 972 pregnant women taking SSRIs and 3,878 matched controls not taking SSRIs. The investigators found that the SSRI group had a significantly increased risk of premature birth (19.3 per cent versus 12.0 per cent), low birth weight (9.0 per cent versus 5.3 per cent), fetal death (1.1 per cent versus 0.4 per cent) and infant seizures (0.4 per cent versus 0.1 per cent). There was no increased risk of birth defects, infection, need for respiratory support, or death up to one year after birth.

While previous studies have reported side effects of SSRIs on the developing fetus, this investigation is the largest ever to examine such a wide variety of effects without relying on patient memory for prescription records.

“These results are certainly unsettling,” said Dr. Mark Walker, a Scientist at the Ottawa Health Research Institute and one of the study’s lead authors. “But untreated depression has also been shown to have side effects on women, and possibly on their fetuses. I feel that it is important that every case be individually assessed to determine the risks and benefits of antidepressant therapy. Patients need to make informed decisions and for those women on SSRIs, we should increase our surveillance.” Dr. Walker is also a physician in the Department of Obstetrics and Gynecology at The Ottawa Hospital and an Associate Professor in the Faculty of Medicine at the University of Ottawa.

The study included SSRIs such as fluoxetine (Prozac) Paroxetine (Paxil) and Sertraline (Zoloft), but the sample size was not large enough to estimate risks for each SSRI individually.

“SSRIs have improved health and quality of life for a huge number of people, but in light of this study, we must be ever more careful to weigh the potential benefits of treatment with the potential risks,” said Dr. Robert Swenson, Associate Chief of Psychiatry at the Ottawa Hospital, Associate Professor of Psychiatry at the University of Ottawa, and a Clinical Investigator at the Ottawa Health Research Institute. “Above all, it is important that anyone taking SSRIs seek professional advice before changing or stopping treatment.”

SSRIs are generally considered the first-line drug therapy in most patients with depression, and approximately 10 per cent of pregnant women suffer from clinical depression.

The research team also includes Dr. Shi Wu Wen, Dr. Qiuying Yang, Dr. Peter Garner and Dr. Carl Nimrod, all from the Ottawa Health Research Institute (an Affiliated Research Institute of the University of Ottawa and the research arm of The Ottawa Hospital). Dr. William Fraser of the University of Montreal and Dr. Olufemi Olatunbosun of the University of Saskatchewan are also co-authors.

Data was obtained from Saskatchewan Health Database records collected between January 1, 1990 and December 31, 2000. The unique database is an invaluable tool for researchers because it tracks prescription drug use over patient lifetimes.

The study was funded by a grant received from The Hospital for Sick Kids Foundation. Both Dr. Shi Wu Wen and Dr. Mark Walker are supported by New Investigator Awards from the Canadian Institutes of Health Research (CIHR).

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