The normal endometrial thickness varies depending on a womans age and menstrual cycle. During menstruation, the endometrial thickness of pre-menopausal women ranges between two and four millimeters. The endometrial thickness increases to between five and seven millimeters during the early proliferative stage, which occurs immediately after menstruation, usually between days four and seven. The endometrial thickness is approximately 11 mm in the late proliferative phase, which lasts for about 11 to 14 days. During the luteal or secretory phase, endometrial thickness grows to an average of 12 to 13 mm, which lasts from days 14 to 28. An endometrial thickness of less than 14 mm is typically considered normal at any stage of the menstrual cycle. After menopause, the endometrium usually measures 5mm or lesser in healthy individuals. However, the designation of normal limits of endometrial thickness rests on determining at which thickness the risk of endometrial carcinoma is significantly increased. While quantitative assessment is important, endometrial morphology and the presence of risk factors for endometrial malignancy should also be taken into account when deciding whether or not endometrial sampling is indicated.