If you take a short-acting contraceptive pill, start taking it on the fifth day of your period, take one tablet once a day for 21 days, and you will have your period 3-7 days after you stop taking it. If menstruation does not occur 9 days after stopping the pill, the possibility of pregnancy should first be ruled out clinically. Although it is a contraceptive pill, but the contraceptive effect does not necessarily reach 100%, due to individual differences, so some people even if you take the pill will be pregnant, so be sure to collect the morning urine to do early pregnancy test. If you are taking the emergency contraceptive pill, if you are taking the emergency contraceptive pill in the first half of your menstrual period, most of the time you will experience withdrawal bleeding after you stop taking the pill, and usually a small amount of bleeding will occur in 3-5 days after you stop taking the pill. If the emergency contraceptive pill is taken in the second half of menstruation, the vast majority will not appear retreating bleeding, because in the second half of menstruation has been ovulated, due to the formation of the corpus luteum, so that the endometrium has appeared to be thickened in the emergency contraceptive pill when the endometrium thickened, then stopping the pill, in the original progesterone effect, there will not be a retreating bleeding of the endometrium, so it also There will be no bleeding, but it does not mean that contraception has failed.