What is the role of interferons in the treatment of multiple sclerosis during pregnancy?

Updated: Aug 20, 2019
  • Author: Carmel Armon, MD, MSc, MHS; Chief Editor: Stephen A Berman, MD, PhD, MBA  more...
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Although interferon beta-1a (IFN-β1a) and interferon beta-1b (IFN-β1b) are category C agents, sufficient data are available from published reports to indicate that they should not be used in pregnant patients, because they impose a high frequency of serious risks on the fetus.

In a rhesus monkey model, high doses of IFN-β1a were not teratogenic but had a dose-dependent abortive effect. [50] In a longitudinal, 3-pronged cohort study involving a group exposed to IFN-β1a and IFN-β1b, a disease-matched unexposed group, and a healthy control group, mean birth weight decreased and rates of miscarriages and stillbirths increased in the exposed group as compared with the control group (39.1% vs 5%). Two major malformations were also identified: an X chromosomal abnormality and Down syndrome. [51]

In another study, 41 pregnancies involving IFN-β1a exposure resulted in 20 healthy full-term infants, 1 healthy premature infant, 9 induced abortions, 8 spontaneous abortions, and 1 fetal death; 1 patient had hydrocephalus, and another was lost to follow-up. [52] These findings were in stark contrast to those of the 22 control subjects, who were exposed to IFN-β1a before, but not during, pregnancy. This control group included 20 full-term healthy infants, 1 healthy premature infant, and 1 infant with a birth-related complication (Erb palsy).

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