Welcome to HCM.
is a progestin prescribed to regularize irregular menstruation
, your doc had rightly prescribed the dose as 3 tabs per day for 21 days, since you missed out doses you started menstruating.
Bleeding generally starts 2 days after the cessation of the dose. It is not advisable to take regestrone tabs during menstruation. If your doc has advised you 2 or 3 months therapy, you can continue taking it after your period stops for the next 21 days, do not miss doses, else bleeding will start before time.
Take food rich in iron and calcium, keep in touch with your gynae. Take care.