Menopause is the permanent end of menstruation and fertility, defined as occurring 12 months after a woman’s last menstrual period. It is not a disease or a condition; rather, it is a natural biological process caused by lowering estrogen levels and ovarian failure. The average age at which menopause occurs in the U.S. is 51. Symptoms can begin three to five years before menopause and include irregular periods, lower fertility, vaginal dryness, hot flashes, disturbed sleep, urinary problems, moodiness and hair loss. Effective treatments include lifestyle changes and hormone therapy.