Endometrial thickness is divided into physiological and pathological causes, as follows: 1. Physiological endometrial thickness is due to the increase of estrogen and progesterone levels in the body. Usually about five days after the onset of menstruation, it begins to show changes in the secretion period, endometrial growth occurs, and it reaches the thickest before the onset of menstruation. With the onset of menstruation, the endometrium is stripped off, and the formation of the menstrual endometrium begins to thin out, and then the next cycle begins again, which is a normal physiological phenomenon. 2. Pathological thickening, including endocrine disorders caused by endometrial shedding incomplete, endometrial inflammation, drug stimulation, endometrial polyps, and endometrial cancer and other conditions. There are many reasons for endometrial thickening, so it is recommended that you go to the hospital in time to get a clear understanding of the cause of the disease and then treat it under the guidance of the doctor.