No contraceptive measure will guarantee 100% contraceptive success and there is a possibility of pregnancy with the pill. First, you still need to take other contraceptive measures, such as condoms and vaginal diaphragms, within 7 days of taking the short-acting pill, otherwise there is a possibility of pregnancy. Secondly, short-acting contraceptive pills need to be taken consistently on a daily basis, stopping after 21 consecutive days and continuing with another cycle of the pill after the end of menstruation. Failure to take the pill as required and failure to make up the missed dose in time can lead to contraceptive failure. Finally, the emergency contraceptive pill, taken within 72 hours after the event, is effective, the earlier it is taken the better, if taken later the chances of pregnancy will increase. The emergency contraceptive pill contains a large amount of hormones and should not be used frequently as it can cause harm to the body, and the effect of contraception will get worse after frequent use.