The prescribing information for Plegridy® (peginterferon beta-1a; Biogen) and Avonex® (interferon beta-1a; Biogen) has been updated to include additional information related to pregnancy and lactation.

Plegridy and Avonex are both indicated for the treatment of relapsing forms of multiple sclerosis (MS), to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease.

The Pregnancy section has been updated with the removal of the “Pregnancy Category C” classification and includes data from a large population-based cohort study on pregnancy outcomes (N=2831) from women with MS. The study included outcomes on 797 pregnancies in women exposed to interferon beta only. 

Findings revealed no increased risk of major birth defects among women with MS exposed to interferon beta products compared to women with MS that were unexposed to any nonsteroid therapy for MS (n=1647) within the study. Moreover, no increased risks were observed for miscarriages and ectopic pregnancies, though the data was limited for these outcomes. 

Additional small studies have suggested that interferon beta exposure during pregnancy may result in a decrease in mean birth weight and may also significantly increase the risk of preterm birth, however neither finding has been confirmed in larger observational studies. 

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With regard to nursing mothers, the updated labeling indicates that interferon beta-1a may be present at low levels in human milk based on limited published literature. The effects of interferon beta-1a on milk production are currently unknown.

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