Motherisk News: Researchers find use of multiple sclerosis drug during pregnancy connected to miscarriage and low birth weight

September 26, 2005

Researchers find use of multiple sclerosis drug during pregnancy connected to miscarriage and low birth weight

(TORONTO) - Researchers at The Hospital for Sick Children (SickKids) have determined that women being treated for multiple sclerosis (MS) with beta interferon therapy have increased risks of miscarriage or low infant-birth weight . This research was reported in the September issue of the journal Neurology.

Beta interferon therapy is the most commonly used therapy for treating relapsing-remitting MS. Based on a protein found naturally in the body that helps to regulate the immune system, it is known to help decrease the formation of lesions, reduce the frequency of relapses and help affect the course of the disease.

The research team discovered that in a study of 36 women, continued use of interferon therapy throughout pregnancy resulted in a 39 per cent increase in miscarriages, a 30 per cent increase in non-live births and a lower overall birth weight in live births.

"In light of this new data, women with MS who become pregnant while taking beta interferon should talk to their physicians and consider discontinuing the drug until delivery," said Dr. Gideon Koren, the study's principal investigator, a senior scientist and director of the Motherisk Program at SickKids, and a professor of Paediatrics, Pharmacology, Pharmacy and Medicine and Medical Genetics at the University of Toronto. "Most importantly, we recommend that women with MS who are pregnant or planning on becoming pregnant speak with their neurologists."

The team also recommends that women with MS resume interferon therapy very soon after delivery if they do not intend to breastfeed. "Discontinuing beta interferon therapy during gestation should not necessarily increase the risk of relapse of MS, as pregnancy tends to reduce such risk," added Dr. Koren.

Study participants were selected through Motherisk, a research program and counseling service based at SickKids that provides information and guidance to pregnant or lactating women and their health-care providers regarding the safety or risk to the developing baby of maternal exposure to drugs, chemicals, diseases, radiation and environmental agents.

Other members of the research team included Dr. Rada Bosovic, Dr. Jacob Wolpin and Rachel Wade, all from SickKids, and Dr. Dan Bauer of the University of North Carolina, Chapel Hill. This research was supported by SickKids Foundation. Dr. Koren is holder of the Research Leadership in Better Pharmacology During Pregnancy and Lactation and The Ivey Chair in Molecular Toxicology at the University of Western Ontario.