Progesterone

Anyone taking or have taken prometrium a.k.a. progesterone (check spelling)? I'm at a cross road if continuing to take it or take my risks of not taking it. The purpose is to thicken the uterine wall so that the fetus can attach properly. However. I have experienced the worst and most severe aide effects to it. White-outs, blurred vision, severe headaches etc. Is there an alternative to progesterone, preferably a natural one?

Please and thanks!

-Mz Madam