What are the safety concenrs with bioidentical oral micronized progesterone?

None: Progesterone is progesterone. All Progesterone comes from the same plant based source and even the synthetic progestins like Provera (medroxyprogesterone) have Progesterone as their base. Micronized Progesterone is exactly Progesterone while synthetic progestins are progesterones that have been chemically modified. Progesterone comes from the ovary or from conversion from the adrenal hormone dhea.