Mention the relationship between concentration of luteinizing hormone and maintenance of endometrial in the human uterus.

The hormone progesterone is secreted by LH; it maintains the uterus lining (the thickness of the uterus wall). If the egg has not been fertilized, the corpus luteum dies and progesterone levels drop. This causes menstruation, where the uterus lining breaks down - this is known as having a period. If a woman becomes pregnant, the placenta produces progesterone. This maintains the lining of the uterus during pregnancy and means that menstruation does not happen.