I haven't yet been diagnosed with Hashimotos as my TSH levels are still be tracked. However I have had 2 blighted ovums in a row before taking thyroxine (50mg daily) but I really only started taking that at around 6 weeks pregnant, I'm now 11weeks.
I'm still not sure IF my thyroid had anything to do with my m/c's.
I do know that I never had a problem until just after I started Bikram Yoga. That is yoga on a warm room aimed at stimulation to the metabolism and thyroid.
It's not proven but my GP is pretty sure it wouldn't have helped.
I have been advised some women develop thyroid issues due to pregnancy. I have not had a problem conceiving, just no fetal development in the first 2, but we have a strong heartbeat at 7 and 9weeks.
PM me if you want to chat.