Oral contraceptive pills taken the day after intercourse are also effective. In general, most of the birth control pills taken the day after intercourse are emergency pills, which will also work as long as they are not used for more than 72 hours, the same as those taken on the first day or immediately after intercourse. Emergency contraceptive pills have an 80% chance of success and a 20% chance of failure. When there is a delay in menstruation, it is best to go to the drugstore and buy a pregnancy test to rule out the possibility of conception. At the same time, emergency contraceptive pills can cause early menstruation, or even confusion, and can also cause withdrawal bleeding. Because each person’s constitution is different, it is recommended to observe, because these manifestations are not that everyone will appear, when the menstrual cycle is chaotic, it is best to go to the hospital to check the endocrine hormones, according to the situation can be adjusted for the cycle.