A significant decrease in menstrual flow at the age of forty is not normal because the normal menstrual bleeding time for women is 3-7 days, while the bleeding volume during menstruation is around 20-60 ml. If the menstrual bleeding time is too short or the menstrual blood volume is significantly reduced, there is a relationship with the thickness of the endometrium. Abnormal changes in the thickness of the endometrium, which can easily cause changes in the amount of bleeding, need to be understood by ultrasound examination of the thickness of the endometrium. In normal women, the thickness of the endometrium varies at different times of the menstrual cycle. For example, the endometrial thickness is about 3 mm at the end of menstruation, about 8 mm during ovulation, and about 1.1 mm before menstruation. If the endometrium is thinning hormone levels need to be checked and estrogen can be used to promote endometrial growth. If the endometrium is abnormally thickened a diagnostic scraping is needed to rule out the risk of endometrial cancer.