Clinician/Patient Dialogue Crucial In Assessing Potential Impact Of Multiple Sclerosis (MS) On Pregnancy, Breastfeeding

Questions have long surrounded the influence of multiple sclerosis (MS) on pregnancy and breastfeeding, and vice versa, especially given the majority of patients are taking disease modifying therapy (DMT) medications.1 Although female MS patients of childbearing age were discouraged from considering pregnancy or breastfeeding, more research suggests that, with proper oversight, the majority of MS patients experience no side-effects. Depending on the severity of the disease, breastfeeding can be an option for some patients, if they do not require DMT medications during that period.2

The PRegnancy In Multiple Sclerosis (PRIMS) study was the first large prospective study to assess the possible influence of pregnancy, delivery, and breastfeeding on the clinical course of MS.2 In that trial, 254 women with MS were followed during pregnancy and through their second year post-partum.2 Researchers found a reduced rate of relapse during pregnancy as compared with the 12 months prior, which was especially marked in the third trimester.2 A significant increase in the relapse rate in the first trimester post-partum was noted, but the relapse rate did not significantly differ from the pre-pregnancy rate at the beginning of the second trimester post-partum.2 In addition, the study found that women who chose to breastfeed experienced fewer relapses and had milder disability scores in the year before and during pregnancy compared with women who chose not to breastfeed.2

Elisabeth Lucassen, M.D., assistant professor of neurology, notes that pregnant women with MS are a difficult population to study, citing the registries kept by all major U.S. pharmaceutical companies that manufacture MS medications as the prime source of retrospective information on pregnancy outcomes and safety, aside from animal data. The impact of various MS drugs on pregnancy is closely tracked since 50 percent of pregnancies are unplanned and involve some early exposure to medication, even if medication is stopped once pregnancy is detected.

Breastfeeding is also important to the conversation as some patients with more severe disease will likely need to forego breastfeeding to resume their medication immediately, while others will choose to breastfeed and resume treatment after their babies are weaned. Lucassen states: “It is vital for neurologists to discuss reproductive plans and the effects of various DMTs with their MS patients of childbearing age, especially since many patients are in their 20s and 30s when first diagnosed.”

Read a summary of MS medications and their effects on pregnancy.

Elisabeth Lucassen, M.D.Elisabeth Lucassen, M.D.
Assistant Professor, Neurology
Multiple Sclerosis, The University Hospital Basel—Switzerland
Neurology, University of Rochester Medical Center, Rochester, N.Y.
Penn State College of Medicine, Hershey, Pa.



  1. Hanson KA, Agashivala N, Wyrwich KW, Raimundo K, Kim E, Brandes DW. Treatment selection and experience in multiple sclerosis: survey of neurologists. Patient Prefer Adherence. April 2014;8:415-22.
  2. Vukusic S, Confavreux C. Pregnancy and multiple sclerosis: the children of PRIMS. Clin Neurol Neurosurg. 2006 Mar;108(3):266-70.

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