The primary objectives of the study were to prospectively record and analyze birth defects and spontaneous fetal losses in women with multiple sclerosis (MS) exposed to Avonex within approximately 1 week of conception or during the first trimester of pregnancy, where the outcome of the pregnancy was unknown prospectively and to prospectively record and analyze pregnancy outcomes in an exploratory fashion of women with MS who stopped therapy, but who may have been exposed to Avonex with approximately 1 week of conception or during the first trimester of pregnancy.