Hi Alear,
My doctor and I agreed to trial Prometrium for just over a year to assess different methods. As you may have heard, Progesterone has not been studied to be beneficial to trans people, and all the evidence supporting its use is anecdotal.
Most practitioners agree it should not be started before attaining Tanner Stage 3 as it matures breast cells, and can mean an end to further development. We also waited until my levels were stable on HRT for six months so we could attribute any changes to the progesterone.
We started at a lower dose orally for some months, then switched to rectal for the same period. While my blood levels didn't change much, I did notice that I didn't get as sleepy on rectal. We then doubled the dose and tried both methods again, with slightly higher blood levels, but no significant differences between methods.
My physical changes were limited to an increase in nipple size, and this happened in the first 3 months. This is one of those 'everyone is different' situations, and others cannot expect similar results to me. I wasn't seeing any further development, so I discontinued taking it. I was trialling this under the supervision of my gynaecologist and an endocrinologist researcher. All uses for Prometrium are 'off label' for trans women as they have not been formally studied or passed by the federal drug agencies.
Hugs,
Allie