There are emergency contraceptive pills that can be taken up to 120 hours after unprotected sex, and the main ingredient of this emergency contraceptive is mifepristone. It is useful to take it within 120 hours after intercourse, and you only need to take one pill. It is also very effective in preventing pregnancy, and the chance of unwanted pregnancy is about 2%-4%. However, it is recommended to take it as soon as possible after intercourse, as the earlier you take it, the more effective it is. If there is a prolongation of menstrual period after taking it, blood or urine HCG should be checked to rule out the possibility of pregnancy. In addition, if there is a contraindication to take emergency contraceptive pills within 120 hours after intercourse, you can choose to place a birth control ring in the uterus, and this method can also be effective in contraception.