Usually, a woman’s endometrial thickness of 8mm is about 7 days away from menstruation, and the normal endometrial thickness before menstruation is about 10mm, but the exact time varies from person to person, and individual women with endometrial thickness of more than 8mm will also have menstruation soon. The thickness of the endometrium varies with the menstrual cycle. Normally, the thickness of the endometrium is around 2-5mm in the proliferative phase, and around 10-12mm in the late secretory phase, and then it enters the menstrual phase. Estrogen and progesterone can cause the endometrium to proliferate and increase the thickness of the endometrium. During menstruation, the level of estrogen and progesterone decreases causing the endometrium to necrolyze and fall off, which makes the endometrium thinner and the thickness of the endometrium is usually around 1-9mm. It is recommended that women avoid coitus during menstruation to avoid infections due to a decrease in the body’s immunity as a result of the shedding of the uterine lining. In addition, women need to maintain a good mood, pay attention to warmth, regular diet and routine, and avoid eating stimulating foods.