Introduction

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease of the central nervous system that is usually diagnosed in a patient's 20s or 30s and is more common in women than in men.1 Given this typical patient profile, many patients with MS are women in their reproductive years. None of the currently approved disease-modifying therapies (DMTs) for patients with MS are recommended for use during pregnancy. Furthermore, all of these medications have been given a pregnancy category B, C, D or X by the US Food and Drug Administration, indicating that in the best case (category B), animal studies have failed to identify potential harmful effects of the medication but long-term safety data in humans are not available or, in the worst case (category X), studies in human patients or animals have identified risks of negative birth outcomes associated with exposure during pregnancy and the medication should not be used by patients who are or may become pregnant.1

Patients should be informed of the potential hazards of medication use during pregnancy, and discontinuation should be considered if patients become pregnant during treatment. However there are few recommendations about when to stop medication before becoming pregnant. Thus, some patients may be taking a DMT when they become pregnant, thereby leading to fetal exposure. In addition, unplanned pregnancies can occur during treatment with DMTs, increasing the chance of accidental exposure to the fetus. Given …