I have had norethisterone once in the past to start AF before my first round of clomid. I hadn't had a period for 70 odd days so was prescribed 5mg norethisterone 3 times a day for 10 days. This time I am taking norethisterone to start AF after a miscarriage and have been prescribed same dose of norethisterone but only for 7 days. Does anyone know why this would be? Also will 7 days work???