Vaginal bleeding after taking emergency contraceptive pills may belong to withdrawal bleeding, or it may be related to menstruation not yet completely clean or ovulation bleeding. 1. Withdrawal bleeding: For women, in order to prevent unwanted pregnancy, they may occasionally take emergency contraceptive pills, so as to achieve the purpose of contraception. Emergency contraceptive pills contain a large number of hormonal components, which may cause women to have withdrawal bleeding, manifested as vaginal bleeding. 2. Menstruation is not yet clean: women who have intercourse just after menstruation may experience vaginal bleeding because the woman’s pelvic cavity is in a state of congestion during intercourse, which, together with the factors of sexual life, may cause localized fissures in the endometrium to bleed, and vaginal bleeding may occur. 3. Ovulation bleeding: If the bleeding is in the middle of two menstrual periods, it may also be a transient bleeding caused by ovulation. It is recommended that women have intercourse 2-3 days after the menstrual period is completely clean, and need to choose other conventional contraceptive measures, such as wearing a condom, intrauterine device, etc., to avoid the blind use of emergency contraceptive pills, the emergence of post-pill vaginal bleeding greater than 7 days or the amount of significantly more than the amount of menstruation or accompanied by other discomforts in a timely manner, so as to avoid affecting the health of the body.