Multiple sclerosis and fertility

Laura Dresser MD (

Dr. Dresser of University of Chicago Medical Center has no relevant financial relationships to disclose.

Anthony T Reder MD, editor. (

Dr. Reder of the University of Chicago received honorariums from Bayer, Biogen Idec, Caremark Rx, Genentech, Genzyme, Novartis, Mallinckrodt, Mylan, Serono, and Teva-Marion for service on advisory boards and as a consultant as well as stock options from NKMax America for advisory work.

Originally released March 13, 2015; last updated October 2, 2020; expires October 2, 2023

Key points


Multiple sclerosis predominantly affects women in their childbearing years and fertility is a frequent concern for these patients.


• Infertility is not considered to be more prevalent in patients with multiple sclerosis.


• Fertility can be potentially be affected by different factors, including symptomatic medications and sexual dysfunction.

Historical note and terminology

Multiple sclerosis primarily affects women of childbearing age and the prevalence of this disease has steadily increased in women over the last 5 decades, with a woman to man ratio of approximately 3:1. This trend starts in adolescence and continues up to the sixth decade of life, when the ratio decreases to around 2:1 (GBD 2016 Neurology Collaborators 2019). Over the past 30 years, there has been a clear shift in the treatment paradigm of multiple sclerosis in pregnant women. Decades ago, physicians believed that pregnancy could worsen the natural course of the disease, as it does some other autoimmune illnesses like systemic lupus erythematosus. The 1998 landmark study Pregnancy in Multiple Sclerosis (PRIMS) provided evidence that contradicted the long-held belief that pregnancy was not safe in multiple sclerosis. This large prospective trial was the first to demonstrate an overall decrease in relapse rate during pregnancy, especially in the third trimester, when compared to the year before pregnancy occurred. It simultaneously raised awareness that there can be increased disease activity in the first 3 to 4 months postpartum. Pregnancy is now widely considered an immune system “tolerant” period for multiple sclerosis patients and some data may even suggest a beneficial effect.

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