Vaginal bleeding after taking emergency contraceptive pills does not indicate successful contraception. The main reason is that emergency contraceptive pills are high potency progestin hormones, which can cause abnormal thickening of the uterine lining, and after stopping the pills, the uterine lining loses the support of the high potency progestin hormones, so withdrawal bleeding will occur. In most cases, withdrawal bleeding occurs when the pill is taken during the first half of the menstrual period, but not when the pill is taken during the second half of the menstrual period. Whether or not there is withdrawal bleeding does not mean that the contraceptive is successful. The contraceptive effect of the emergency contraceptive pill is still very good, up to 98%, but not 100%. It is recommended to rule out the possibility of pregnancy if you do not have your period when you should have one after taking the emergency contraceptive pill.