The cause of delayed menstruation after taking the emergency contraceptive pill is mainly related to the time of taking the pill. If the patient takes the emergency contraceptive pill exactly 2-3 days before the normal menstruation is about to come, the endometrium will continue to be in the secretory phase due to the intake of large doses of exogenous progestin, which will not be able to peel off and bleed in time, and naturally, the menstruation will not come on time. When the large amount of progestin intake is metabolized and cleared, withdrawal bleeding will occur, which is also manifested as a postponed menstrual flow. Occasional use of the emergency contraceptive pill has a temporary effect on menstruation and no special treatment is needed. If the period is delayed for more than 7-10 days, further examination is needed to rule out early pregnancy. If you take emergency contraceptives frequently, it may easily cause irregular menstruation or even premature ovarian failure.