Progesterone is a female sex hormone involved in many processes throughout the body. One of the main purposes for progesterone is to act as a moderator for estrogen by balancing its actions and ensuring healthy cell growth. A decline in progesterone as a result of aging can have negative effects on a woman’s health. Prior to menopause, progesterone protects women against uterine cancer, breast cancer, osteoporosis, and heart disease. Some symptoms that one may be low in progesterone include pain and inflammation, headaches, depression and anxiety, irritability, insomnia, and low sex drive.