Biogen Multiple Sclerosis Pregnancy Exposure Registry

Key Inclusion Criteria:

* Patient consent
* Patient has a diagnosis of MS.
* Documentation that the patient was exposed to a Registry-specified Biogen MS product during the eligibility window for that product.
* DMF: Exposure since the first day of her last menstrual period (LMP) prior to conception or at any time during pregnancy.
* Peginterferon beta-1a: Exposure since 17 days prior to the first day of her LMP prior to conception or at any time during pregnancy.
* DMT unexposed pregnancy cohort: Never received DMT therapy
* Patient agrees to sign the Release of Medical Information Form, thereby permitting the Registry to contact her health care provider (HCP(s)) and the pediatric HCP for medical information.

Key Exclusion Criteria:

* The outcome of the pregnancy (i.e., pregnancy loss or live birth) must not be known at the time of enrollment.
* Initial maternal health assessment upon confirmation of pregnancy does not preclude participation in the Registry unless a patient tests positive for a medical condition associated with negative pregnancy outcomes (e.g., toxoplasmosis screen and syphilis \[venereal disease research laboratory test and rapid plasma reagin test\] blood screen) in the opinion of the healthcare provider (HCP).

NOTE: Other protocol defined Inclusion/ Exclusion criteria may apply.