Whether a sudden decrease in menstrual flow is important or not depends on the patient’s specific situation and needs to be analyzed on a case-by-case basis. The normal menstrual volume for women is 30-80 ml, and less than 30 ml is a low menstrual volume. Low menstrual volume is a symptom of menstrual disorder, which means that there may be endocrine abnormalities in the body. If a younger patient has a sudden decrease in menstrual flow, it is important to have a hormone test and a gynecological ultrasound to monitor the estrogen level and to be alert for premature ovarian failure. If the decrease in menstrual flow is due to premature ovarian failure, estrogen supplementation can be used to maintain the dynamic balance of hormones and normalize menstrual flow. If the patient is around 50 years old, it is considered to be entering perimenopause, which is a normal condition and does not require special treatment. If women with fertility needs experience a sudden decrease in menstrual flow, they should pay attention to it. Irregular menstruation may affect conception, so it is recommended to consult a gynecologist in time to clarify the condition and treat the symptoms. You can take drugs to activate blood circulation and improve symptoms under the guidance of a doctor.