we do not apply the Prometrium, but we have very extensive experience with the using of the Utrogestan, which has the same composition as Prometrium 100mg. We use them mainly in the cycles without corpus luteum (FET, oocyte donation), but also for the cycles with corpus luteum (fresh IVF cycles, FET in natural cycles) support. The usual dosing is from 2 capsules to 4 capsules daily per os, the vaginal application is also possible.