Sudden decrease in menstrual flow, if there is a history of abortion, scraping, removal of the ring, history of infection, need to consider the presence of endometrial damage, endometrial adhesions, endometrial tuberculosis infection, endometritis, etc., and need to do a hysteroscopy to clarify the diagnosis. After determining the above diseases, it is necessary to take antibiotics, or estrogen or progesterone, to repair the endometrium, or to do hysteroscopic electrocision to separate the adhesions, etc. Decreased menstrual flow can also be caused when the hypothalamus is suppressed due to mental stress, overwork, improper weight loss, and eating disorders. You need to maintain a good lifestyle, strengthen physical exercise, maintain regular eating and sleeping habits, quit smoking and alcohol, and develop regular eating habits, which can improve the menstrual flow.