For the endometrium 3mm normal or not, it should be judged in conjunction with the different phases of the menstrual cycle. If the thickness of the endometrium is 3mm during the menstrual period, it is a normal condition. However, if the thickness of the endometrium is 3mm during the second half of the menstrual cycle, 7-8 days before the onset of menstruation, the ultrasound suggests that the endometrium should be relatively thin, which is an abnormal condition, and it should be considered in conjunction with whether or not the woman has had any previous abortions or curettage. If there is a history of the above, it is possible that the endometrium is not proliferating or reacting due to uterine adhesions, resulting in a corresponding thin state. It is best to consider the possibility of subsequent infertility or low menstrual flow, and to perform a hysteroscopy or, if adhesions are present, to perform an adhesion detachment.