If the patient usually has very regular menstruation, and after an occasional ovulatory bleeding, her menstruation is delayed and does not come normally, the following three possibilities are considered: First, the bleeding that occurs in the middle of the patient’s menstruation is not ovulatory bleeding, but early menstruation. The bleeding during ovulation is usually very small, with a drop of blood or a white belt with blood, and it clears within 3-4 days. If the bleeding in the middle of the period lasts for about 5 days, and the amount of bleeding is like the amount of menstruation, then it should be considered as early menstruation. Second, the possibility of pregnancy, the chance of pregnancy during ovulation is very high, so when patients have delayed menstruation, they must check the blood or urinary chorionic gonadotropin to determine whether they are pregnant. Thirdly, episodic delayed menstruation can occur because women are easily disturbed by external factors, such as emotional changes, work and study stress, seasonal changes, etc.