Multiple sclerosis (MS) is an autoimmune disease of the central nervous system affecting predominantly women of childbearing age; therefore, issues of conception, pregnancy, and delivery become of significant importance to patients and treating physicians. This article discusses the immunological and clinical effects of pregnancy on the course of MS, clinical outcomes of Pregnancy in Multiple Sclerosis (PRIMS) trials, the available data on safety and efficacy of immunomodulating MS treatments and symptomatic treatments for pregnant and lactating women, and specific issues of MS management at the time of pregnancy. The data related to estrogen-based MS therapies currently or previously in trials are reviewed. Pregnancy does not appear to be associated with adverse outcomes in MS patients. Some evidence suggests possible beneficial effects, although clear prospective data of sufficient length are limited. Long-term relapse rates and disability progression do not seem to be affected by pregnancy in MS patients. The use of immunosuppressive or immunomodulatory agents in pregnancy is not routinely advisable.