Plan B says it doesn't cause miscarriage. Directions says to take pill 1-3 days after sex. I  took a Plan B pill 3 days after sex.  About a week later I had rubbery looking discharge and thought nothing of it except "what the hell is this?" I wasn't getting a period and later found out from the doctor I had a miscarriage. I know it was because I took a Plan B. Plan B can cause miscarriage if it is not taken right away.