Medications as interferon beta 1a ( Avonex and Rebif), and interferon beta 1b( Betaseron) as well as glatiramer acetate ( Coaxone), also known as disease-modifying medications, are not approved during pregnancy, because they have the potential to lead to a miscarriage.  Disease-modifying medications should be ceased at least 1-2 menstrual cycles before a woman is trying to conceive; the medication can be resumed right after delivery, granted the fact that the woman chooses not to breast-feed the baby.

Among other medications that have the potential of harming a pregnancy are mitoxantrone ( Novantrone) and other chemotherapeutic agents like cyclophosphamide, methotrexate and azathioprine.