What Is The Purpose Of Wysolone During Frozen Embryo Transfer Pregnancy?

Hi... I am 37 y.o . I have conceived through frozen embryo transfer almost 3 months now. . This is my second pregnancy. First one was too (FET) n I have a 5 year old. I have been prescribed wysolone 10 mg along with progynova 2 mg 6 tablets a day n geston injections 100 mg daily. Want to know why my doc is giving me wysolone... as I didn t get them in my first pregnancy