Estriol and progesterone: a new role for sex hormones.

The physiological states pregnancy and parturition are undoubtedly associated with clinical changes of most of the autoimmune diseases. An altered Th1/Th2 balance has been proposed as an underlying mechanism. A pregnancy has protective effect on Th1-mediated autoimmune diseases, and a deteriorative effect on Th2-mediated autoimmune diseases. Numerous studies, both experimental and clinical, imply that estriol and progesterone, at high doses (such as those achieved during pregnancy), have potent anti-inflammatory and neuroprotective roles. These studies, as well as a further investigation of pregnancy-associated immunomodulation, can be used to advance and develop a new therapy approaches.