The emergency contraceptive pill is no longer useful after 72 hours. This is because the emergency contraceptive pill contains large doses of progestin, and its main contraceptive effect is to inhibit ovulation in women, which means that after taking the pill, no eggs will be released from a woman’s ovaries. Even if you have intercourse at this time, there will be no egg, so there will be no way for the sperm to combine with the egg, so it is impossible to get pregnant. If you take the pill after 72 hours, an egg will have been released and the egg may combine with the sperm in the room to form a fertilized egg and become pregnant. Therefore, after unprotected sex, you must take the emergency contraceptive pill as soon as possible, the earlier the effect, the better, not delayed until after 72 hours, after 72 hours and useless.