The thickness of the endometrium generally falls within the normal range of 4-15mm, with 7mm being the normal value. The thickness of the endometrium generally varies with the menstrual cycle, the functional layer of the endometrium is the last before menstruation and may reach 15mm, with the onset of the menstrual cycle, the endometrium sheds, the functional layer of the endometrium gradually becomes thinner, so the endometrium may be 4mm during menstruation, with the formation of ovulation, the endometrium may reach 8mm after ovulation. The endometrium may reach about 8mm after ovulation. Before menstruation, the endometrium may reach 15 mm due to the secretion of progesterone, so the thickness of the endometrium is uncertain and varies with the menstrual cycle.