MS & Pregnancy: What's Safe?

Q)What are the considerations and recommendations for pregnancy and breastfeeding in women with multiple sclerosis? When should women discontinue their disease-modifying therapies?

Multiple sclerosis (MS) is an inflammatory, demyelinating, de­gen­erative disease. Three times more common in women than men, it may affect pregnancy planning and childbearing experiences.⁶ Evidence demonstrates a reduction in annualized relapse rate during pregnancy and the postpartum period with exclusive breastfeeding. Therefore, pregnancy and exclusive breastfeeding provide a favorable immunomodulatory effect in women with MS, which combats the increased relapse risk associated with the postpartum period.^7,8

Reproductive education—including conception, pregnancy, and breastfeeding—is critical for patients with MS and their partners during a woman’s childbearing years. However, women with MS do not require special considerations during pregnancy unless they have remarkable disability. As soon as these women and their partners decide upon pregnancy, a plan should be established that includes a discussion about potential risks to the fetus due to drug exposure, as well as risks to the mother. The goal should be to minimize risk for disease activity and optimize the health of the baby.

Use of DMTs during conception, pregnancy, and breastfeeding. All disease-modifying therapies (DMTs) are usually discontinued during pregnancy and breastfeeding. Common practice among MS experts is to discontinue DMTs prior to conception, with a few exceptions. There is no consensus about timing of discontinuation and washout period for each DMT. The decision is based on the half-life of each DMT, the opinions of the woman and her partner, and risk tolerance. Note: For the purposes of this discussion, the old pregnancy category designations are used, since they are familiar to clinicians. New guidelines took effect in June 2015; Table 3 outlines the change in format.

Injectables. Glatiramer acetate (GA) is the safest drug in relation to pregnancy and breastfeeding (category B). There is no evidence of congenital malformation or spontaneous abortion. The common recommendation is to discontinue the drug one to two months before conception, although some clinicians allow continuation of the injections throughout pregnancy and into breastfeeding.

Interferon-ßs are category C and therefore pose minimal risk for the fetus. The washout period before conception is two to three months, varying among ­clinicians. Although there is no evidence of spontaneous abortion or birth defects in humans, animal data show increased risk for abortion.⁹

Both GA and interferon-ßs are large molecules; there is a very minimal chance that the medication will transmit to the baby via breast milk. Thus, both DMTs are considered safe during lactation.⁷

Oral MS medications. The three approved MS oral medications are fingolimod, dimethyl fumarate (DMF), and teriflunomide. Fingolimod and DMF are both category C. Women on DMF must discontinue use of the medication one month prior to conception due to its short half-life. There are no reports of birth defects or spontaneous abortion in women taking DMF. Fingolimod needs to be discontinued two months prior to conception. Animal data show evidence for teratogenicity and embryolethality at lower doses of fingolimod than those used in humans.⁷

Teriflunomide is category X, posing high risk for the health of the fetus. It stays in the blood for approximately eight months after discontinuation of use. Animal data show teratogenicity and embryotoxicity; therefore, teriflunomide is contraindicated in pregnancy. Women on teriflunomide who plan to become pregnant need to undergo an elimination procedure with cholestyramine or charcoal.