It was suggested that I might better benefit from taking estriol than Rebif since it is known that women who have ms no longer exhibit symptoms when they are pregnant. I understand this approach is used in parts of Europe and that their are clinical trials in the USA right now. However, my doctor (not my neurologist), who practices more wholistic medicine, suggested I might want to try estriol. She feels it is safe in the doses given and for the fact that it is an estrogen that is "weak", unlike other estrogens.