In our usual outpatient work, we often see young women who come to the clinic with irregular periods and after repeated questioning, we find that they are in the habit of taking emergency contraceptive pills regularly to prevent pregnancy. Sometimes they even use emergency contraceptive pills 7-8 times in a month. As a result, irregular vaginal bleeding occurs, which they think is irregular menstruation. They have little knowledge about some contraceptive aspects and these behaviors will bring many hidden dangers to their body and endocrine system. Here I will inform you some principles and precautions of taking emergency contraceptive pills. 1.A remedy taken within a short time after the discovery of contraceptive failure is called emergency contraception. Emergency contraception is a remedy after the failure of contraception by taking the pill within 72 hours after intercourse without contraception or by placing a copper intrauterine device within 5 days. First of all, emergency contraception can only be used for unprotected sex and can only be taken once in a menstrual cycle, and other reliable contraceptive measures should be used for sex after this cycle. Secondly, emergency contraception is only a temporary remedy and should never be used repeatedly as a regular contraceptive method. Thirdly, if emergency contraception fails and pregnancy occurs, the incidence of newborn malformations is high and the pregnancy must be terminated. Finally, it should be reminded that emergency contraception should be carried out under the guidance of a doctor. Fourth, the principle of contraceptive pills is to use a very large amount of drugs to inhibit the function of the ovaries, inhibit ovulation, repeatedly eat this contraceptive pill, will interfere with the function of the female ovaries, so this remedy after the failure of contraception can not be used often. 2, after the occurrence of pregnancy to drugs or surgical methods to terminate pregnancy, called abortion, is another effective remedy after the failure of contraception.