12. Females of childbearing potential (FCBP) must have a negative serum pregnancy test with a sensitivity of at least 50 mIU/mL within 10 -14 days prior to and again within 24 hours of prescribing lenalidomide (prescriptions must be filled within 7 days) and must either commit to continued abstinence from heterosexual intercourse or begin TWO acceptable methods of birth control, one highly effective method and one additional effective method AT THE SAME TIME, at least 4 weeks before she starts taking lenalidomide.