Ovulation does not usually occur during withdrawal bleeding. Withdrawal bleeding is usually caused by bleeding due to the combined withdrawal of hormones in the body, especially after the withdrawal of estrogen and progesterone, which results in the endometrium not being able to grow normally, causing the endometrium to shed and withdrawal bleeding to occur. Generally at the time of ovulation, estrogen needs to reach its peak value to trigger ovulation, and during withdrawal bleeding, estrogen will drop. Therefore, ovulation does not normally occur. Retreating bleeding is usually bleeding after the application of medication, usually after taking emergency contraceptive pills or progesterone, which may lead to irregular menstruation and endocrine disorders. If there is any abnormality after the occurrence of withdrawal bleeding, it is recommended to consult a doctor in time. Moreover, after the occurrence of withdrawal bleeding, effective contraceptive measures are also needed for those who have sex without fertility requirements.