The normal thickness of the endometrium is related to the different times of a woman’s menstrual cycle and also to her age, for example, just after menstruation, the patient’s estrogen and progesterone levels are low and the endometrium has just been exfoliated. The endometrium appears to be proliferating, so the thickness of the endometrium needs to be more than 0.8cm in order for the fertilized egg to be successfully implanted. Before menstruation, a woman’s endometrium must be at least 1.0 cm thick in order to have a normal menstrual flow. This is the variation of endometrial thickness in women of childbearing age; for postmenopausal women, it is required that the endometrium must be less than 0.5cm, and it is best if it is 0.2-0.3cm.