What happens to my period after norethisterone?

Varies. Norethisterone is a progestin, similar to the progestone your body makes after ovulation. How it affects your period depends on when you take it and for how long. If you take it throughout the month it will normally make your period lighter. If you take it after ovulation, it may delay your bleeding. If you just take for a couple of days, you're likely to bleed after stopping it.