The causes of low menstrual flow despite normal menstrual cycle are as follows: 1) Low menstrual flow on the first day of menstruation due to environmental changes, exposure to cold, stagnation of qi and blood stasis, etc. 2) Low menstrual flow due to damage to the uterine lining due to excessive scraping or partial adhesion of the uterine cavity 3) Low menstrual flow due to endometriosis such as endometrial tuberculosis 4) Low menstrual flow due to congenital malformation of uterus or small uterine development 4) Low menstrual flow due to congenital malformation of uterus or small uterine development 4. Congenital uterine abnormalities or small uterine development can also lead to low menstrual flow. Therefore, when a woman has normal menstrual cycle and low menstrual flow, it will easily lead to pregnancy or repeated abortions, and she needs to go to the hospital in time to do gynecological ultrasound and sex hormone examination, and early use of medication or surgery to deal with it.