I was listening to a podcast, which covers immunity/autoimmunity. According to the doctor, women can sometimes produce more prolactin, which puts a stress on the body, increasing likelihood of developing autoimmune disease. Hypothyroidism stimulates the production of prolactin, and so causes autoimmune disease.
I'm a little confused if this is the case though, because for most of us, the autoimmune disease comes first, and the hypothyroidism comes later? It's just hat doctors don't test for autoimmune disease until after they diagnose hypothyroidism...
If anyone wishes to listen to what she says, here's the link, and that little section starts at 23mins 40s: