Emergency contraceptive pills, because of the relatively large amount of hormones, can easily lead to menstrual disorders, early or delayed menstruation is normal, especially the occurrence of post-pill withdrawal bleeding. If you take emergency contraceptive pills for a week and then have your period, this is a kind of hormonal withdrawal bleeding after taking the pills, which is a normal phenomenon. If the amount of bleeding reaches the amount of menstruation, it is considered a period, and the date of the next period should be counted from this time onwards. If the amount of bleeding does not reach the amount of menstruation, or is significantly less than the amount of menstruation, this bleeding cannot be considered a menstruation, and the date of the next menstruation has to be calculated according to the previous days.