Hi karin
The only progesterone ( ie the "natural" bio-identical one) licensed to be used as protection for the womb as part of HRT is Utrogestan (micronised progesterone).
Although this is designed to be taken orally in UK many of us use it vaginally, often with the support of our GP, some through private consultants, others through just doing it. I use it this way with the support of my GP. She prescribes it normally but I just take it vaginally.
Research seems to show that lower doses are needed to keep the lining thin when used vaginally - because it goes straight to the uterus where it is needed. However the French instructions (I have a translation of the leaflet) only suggest varying the route of delivery (ie to vaginal) if side effects are experienced from oral use, but at the same dose as when used orally.
Unfortunately the 200 mg oral dose has been discontinued, but bizarrely the same product is prescribed for fertility for vaginal use and the 200 mg dose is still available! I just got some more from the pharmacy at my GP practice today, and they just gave me double the amount of 100 mg capsules with the instruction just to double the quantity.
I use the 200 mg dose vaginally for 12 days every 6-8 weeks - instead of 200 mg orally every 4 weeks, and it seems to keep my lining thin, although once a year my GP recommended taking a course of norethisterone to make absolutely sure - which I did in August.
In the past I used Cyclogest - which is designed to be used vaginally or rectally - but it is not licensed as part of HRT, again I think it's usually a fertilty product. My GP prescribed 400 mg ( ie two capsules) per night for 11 days per 4 weeks, but I found it gave me migraines so I think the dose was too high. Eventually my bleeds stopped so probably the dose was high.
Good luck with your GP and let us know how you get on!
Hurdity x