Endometrial hyperplasia is the abnormal or excessive thickening of endometrium, the lining of the uterus. The endometrium thickens every month in order to get ready for pregnancy. In case the pregnancy does not occur, then the endometrium is shed. This shedding process of the lining is known as menstruation or menstrual period. Normally, majority of the women have the menstrual period which lasts for approximately 28 days. The whole process is controlled by the two hormones in the body: the estrogen and progesterone. If these hormones are unbalanced or are not available at all, the cells may grow abnormally which may result in endometrial hyperplasia.