Starting IVF and norethisterone on day 21 !

[Sadgirl28]

Does anybody know if I will have short or long protocol with me starting norethisterone on day 21 of my cycle , I haven’t had a plan yet but was told to start taking norethisterone until they say to stop , just wondering if anyone took same medication and what protocol was you , thank you

Also wanted to ask what does norethisterone actually do to the body as by that time I have already ovulated naturally in the cycle so I’m a bit confused what’s it’s supposed to do. Stop my next cycle from coming ?