I read about a womasn who had a cesarean section and smoked marijuana a week later. She said the next day she lost about a cup of blood all at once, soaking a pad in the process, and it running down her legs. And at the hospital they found a fist sized clot and she lost more blood there. They said her uterus felt lose and probably got lazy and stppped contracting. Could the marijuana have caused that? And can cigarettes of alcohol cause that as well?