Many women are confused as to why they can still get pregnant after taking the pill if it is a contraceptive. The truth is that no method of birth control is 100% effective, including tubal ligation and IUD placement. Yutin also has a 4% chance of pregnancy when used correctly, and a higher failure rate if people don’t use it correctly within the prescribed time frame. Here is the correct time to take the emergency contraceptive pill. The mechanism of action of the emergency contraceptive pill is to inhibit ovulation and prevent the fertilization of the egg, and to increase the viscosity of the cervical mucus, which prevents sperm penetration, thus acting as a fast-acting contraceptive. The pill is administered by taking one pill within 72 hours after intercourse, followed by a second pill 12 hours apart. The specific time and operation of the pill are as follows: a. The emergency contraceptive pill should be taken within 72 hours after unprotected intercourse (preferably within 12 hours) as early as possible, otherwise the efficacy of emergency contraception will be reduced due to the delay in the use of the pill, and there is almost no effect when taken after 72 hours. Second, the interval between the two doses of emergency contraceptive pills can not exceed 12 hours, otherwise it will affect the effectiveness of contraception due to the decline in blood concentration. If you miss the second dose, the interval is more than 15 hours, then the first dose will be ineffective and you need to take the pill again. Strictly following the above steps and combining them with the instructions of the emergency contraceptive pill will help to maximize the effectiveness of contraception. However, from the point of view of health, this can be very harmful to women. Because of the high hormonal content of the emergency contraceptive pill, multiple doses can greatly increase the probability of menstrual disorders and have an effect on ovulation and the endometrium, so the emergency contraceptive pill should not be used as a regular contraceptive and should not be used continuously, preferably no more than three times a year. References: [1] Wen Caihe. Contraceptive pills [J]. Health Expo. 2015(5):37