The definition of endometrium is layers of mucus, which create the membrane that lines a woman's uterus. This membrane sheds during a woman's menstrual cycle and then renews the next month. The purpose of the endometrium is to provide a protective layer of tissue in order to support a developing fetus. However, when impregnation does not occur, the endometrium membrane will be shed, thus creating the menstrual period.
Low levels of estrogen: Low estrogen levels have been linked to a thin endometrium. If a woman experiences these low levels, their endometrium is unable to naturally thicken.
Insufficient blood to the endometrium: Just as any other tissue needs a steady blood supply to grow; so does the endometrium. If the blood flow is hindered in any way, the blood supply may not be able to produce sufficient means for thickening the endometrium.
Damage to the endometrium: This damage can be the results of several different problems and may lead to the inability for the endometrium to thicken. If the endometrium is unable to thicken, then a woman will experience infertility. Any three of these reasons may be the cause of this infertility.