A normal period lasts 2-8 days, with an average of 4-6 days. If it is less than 2 days, the period is too short. The most common causes are abnormal ovulation, no ovulation, and the endometrium is thin, so the bleeding is less. It can also be seen after abortion causing endometrial damage, adhesions in the uterine cavity, and low and short menstrual periods. The most common cause endocrine disorders are if menstruation lasts longer than 8 days. It can also be due to abnormal ovulation, no ovulation, no progesterone secretion. The endometrium is under the action of estrogen for a long time, endometrial thickening breakthrough bleeding occurs, bleeding time is longer, can also be seen in endometrial polyps, uterine fibroids, all these causes can cause prolonged menstrual period.