Why Is Meprate Tablet Prescribed?

Hi, i had continuous menstruation for more than a month. It was in the form of large blood clots. my gynac prescribed PAUSE MF till the bleeding stops and Meprate 10mg along with it (1 daily for 10 days). After the course finishes i might have to do a 3 month course of contraceptive tablets. 1)what is the meprate tablet for? 2)Are contraceptive tablets safe(last year i did the same course and had put on lot of weight after) 3) why does this happen? Thanks Sonali