Emergency contraceptives are hormones, commonly known as ethinyl estradiol, yutin, gold yutin, and mifepristone, which can be divided into estrogen, progestin, and progestin antagonists. Most of the pharmacies buy yutin or gold yutin, mainly through the inhibition of ovulation or affect the degree of endothelial tolerance into, and interfere with the fertilization of the egg to play the principle of contraception. But the emergency contraceptive pill can only play 80%-90% of the contraceptive effect, there will be a small percentage of contraceptive failure rate, so the delay in menstruation for more than 7 days should be actively tested for pregnancy. If you miss the time to take the pill, you can wear an intrauterine device. If the age is relatively young it is not recommended to take the pill, it may lead to endocrine disruption and should be actively defensive measures.