An endometrial thickness of 23mm is not normal. The endometrium is a tissue attached to the uterine cavity and its thickness is not static, it fluctuates within the normal range as the menstrual cycle changes. The endometrium of women with regular menstruation is divided into three phases according to the menstrual cycle: proliferative phase, secretory phase, and menstrual phase. the proliferative phase is the 5-14 days of the menstrual cycle, which corresponds to the follicular phase in the ovarian cycle, and the thickness of the endometrium is about 3-5mm. the secretory phase is the 15-28 days of the menstrual cycle, which corresponds to the luteal phase in the ovarian cycle, and the thickness of the endometrium is up to 10mm in the late secretory phase, that is, the 24-28 days of the menstrual cycle. Therefore, an endometrial thickness of 23mm is on the thick side, and endometrial pathology and other possibilities cannot be ruled out, so timely consultation is recommended to clarify the cause.