Dr. Prior has studied women?s menstrual cycles, perimenopause and the causes for and treatment of osteoporosis. She has shown that regular cycles (with enough estrogen) commonly do not produce sufficient progesterone (anovulation or short luteal phases). More versus fewer ovulatory disturbances within regular cycles are related to significant spinal bone loss in healthy women ages 20-45. She has proven in controlled trials that the ovarian hormone, progesterone, is effective treatment for menopausal hot flushes. She also documented that progesterone is safe for heart health. Dr. Prior is internationally known for her research showing that progesterone increases bone formation by stimulating osteoblasts. More recently, she has documented that estrogen levels, besides being unpredictable, are significantly higher than normal in the perimenopause, the 3-10 years of changes before menopause.