Low menstrual flow for a long time, the main causes of this symptom include: 1, cervical adhesions, repeated abortion surgery, cleaning surgery, IUD removal and other surgical procedures, damage to the cervix, adhesions occur during the healing process of the cervix, affecting the normal discharge of menstrual blood, resulting in low menstrual flow and prolonged periods; 2, smoking, tobacco contains a large number of nicotine, tar and other harmful chemicals. These chemicals will affect the normal endocrine function of the ovaries, and even lead to premature ovarian failure, smoking women have a significantly higher chance of menstrual disorders, low menstrual volume; 3, intrauterine device, women who take the intrauterine device placed in the way of contraception, if the device is not adapted to the placement of the device, or the device is placed for too long, will also make the menstrual period prolonged, menstrual volume reduced.