A period of 25 days is definitely an abnormality, and a woman’s normal menstrual period should be 3-8 days. If the period is less than three days and clears in only 1-2 days, it is called a prolonged menstruation. If the period is not cleared for more than eight days and has reached 25 days, it is a prolonged period. There are many causes of prolonged periods, the more common ones are dysfunctional uterine bleeding, which is abnormal uterine bleeding caused by endocrine disorders. There are also organic diseases, such as fibroids, especially submucosal fibroids or huge fibroids between the muscle walls, which may lead to prolonged periods. Endometrial polyps or maladjustment of the IUD ring can also cause prolonged periods. Some other related medical disorders, such as thrombocytopenic disorders, or coagulation disorders, may also cause prolonged periods. Individual patients with abnormal thyroid function and thyroid disorders may also cause prolonged periods. The exact cause must be clarified by a relevant examination at the hospital. If the period lasts more than 25 days and there is a history of sexual intercourse, you should also consider whether the bleeding is caused by abortion caused by pregnancy, resulting in failure to clear. A woman’s menstrual cycle is called a menstrual cycle when it is calculated from the first day of the last period to the day before the next period. A woman’s menstrual cycle is between 21-35 days, which is within the normal range.