Hormones do seem to play a role, to a varying degree, in the effects of MS symptoms. Although there is a definite relationship between hormones, the immune system and MS, the precise nature of their effects are unknown. Yes, pregnancy, with high estrogen levels, seems to be protective however there are many other proteins secreted by the placenta like alpha feto protein that could also play a role. The exact role of estrogen and progesterone are not yet sorted out and therefore hormonal manipulation is not yet a real clinical option for non- menopausal women.
Estrogens have risks including increased clotting and breast cancer.
One must know the benefits to weigh them against the risks. This is known in menopause with heart disease, Alzheimer's risk, osteoporosis etc. I am in the midst of peri-menopause, and have set up an appointment with my gynecologist for review. I had a partial hysterectomy. I know there is a reduction of estrogen taking place.