Doing a cursory google search for articles on Pregnancy and Multiple Sclerosis, I found these articles. Yes, Estriol is currently being studied in a clinical trial. In fact, they are recruiting in this clinical trial. Here's the link:

http://www.clinicaltrial.gov/ct2/sho...ing%22&rank=63



http://brain.oxfordjournals.org/cgi/...act/127/6/1353

http://www.ncbi.nlm.nih.gov/pubmed/16413965

http://msj.sagepub.com/cgi/content/abstract/13/1/33

http://www.news-medical.net/?id=4375