The duration of a woman’s period is 3-7 days, less than two days is too short a period and more than seven days is too long a period. The most common cause of a short period is damage to the endometrium and adhesions in the uterine cavity after abortion, uterine evacuation or intrauterine surgery, resulting in a short period and a low menstrual flow, or it may be caused by an endocrine disorder with no ovulation and a thin endometrium. If the menstruation lasts more than seven days, it is too long. The most common causes are endometrial polyps, submucosal fibroids, and endocrine disorders. Endocrine disorders mainly manifest as luteal insufficiency, luteal atrophy insufficiency, and premature atrophy of the corpus luteum, all of which can result in prolonged menstruation and need to be treated according to the specific cause.