There is a 20% chance of pregnancy after taking the emergency contraceptive pill. The emergency contraceptive pill works by changing the morphology and function of the endometrium, causing the cervical mucus to become sticky, thus preventing the passage of sperm and their implantation for contraceptive purposes. However, no method of contraception is completely effective and there is a certain chance of failure. Pregnancy after taking the emergency contraceptive pill is mostly related to the limitations of the pill itself and the wrong time or method of administration. Only when the emergency contraceptive pill is taken correctly can it be effective. In the use of emergency contraceptive pills, precautions are as follows: 1, the correct use of emergency contraceptive drugs, that is, within 72 hours after unprotected sex, can play a contraceptive role, the earlier the use of time, the more reliable the effect of contraception; 2, when taking emergency contraceptive pills can not drink alcohol, because alcohol will affect its metabolism; 3, dizziness, vomiting and other drug side effects during the pill, the lighter through rest 4.Emergency contraceptive pill is only effective for the previous sex life, if you have sex after taking it, you need to take effective contraceptive measures; 5.Emergency contraceptive pill is recommended not to use more than 3 times a year, and can not replace conventional contraceptive methods. If you get pregnant after taking oral contraceptives, it is recommended to choose to terminate the pregnancy, you can choose drug abortion or artificial abortion.