Jerilynn C. Prior BA, MD, FRCPC, ABIM, ABEM is a Professor of Endocrinology and Metabolism at the University of British Columbia. She has spent her career studying menstrual cycles and the effects of the cycle's estrogen and progesterone hormones on women's health. She is the founder (2002) and Scientific Director of the Centre for Menstrual Cycle and Ovulation Research (CeMCOR), which actively researches women's health. She is also Director of the BC Centre of the Canadian Multicentre Osteoporosis Study (CaMOS) that is studying osteoporosis, fractures and bone density. Prior has studied women's menstrual cycles, perimenopause, and the causes for and treatment of osteoporosis. 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. She is widely sought as a speaker for professional and lay audiences and is the author of the award-winning book Estrogen's Storm Season: Stories of Perimenopause, an informative book about perimenopause told in story format. With Susan Baxter PhD, sociologist/medical journalist, Prior is author of Estrogen Errors - Why Progesterone Is Better For Women's Health (2009). She has authored scientific papers numbering over 200 and holds 6 patents. She is an Honourary Alumna of the University of British Columbia Faculty of Medicine and was awarded its Distinguished Medical Research Lecturer Award (2002). She has numerous other honours including the Ann Voda Lifetime Achievement award of the Society for Menstrual Cycle Research.