Menstrual cycle of progesterone, the uterine lining changes to prepare for potential implantation of an embryo to establish a pregnancy. If implantation does not occur within approximately two weeks, the corpus luteum will involute, causing a sharp drop in levels of both progesterone and estrogen. The hormone drop causes the uterus to shed its lining in a process termed menstruation. Menstruation also occurs in closely related primates (apes and monkeys). The average age of menarche is 12–15. They may occasionally start as early as eight, and this onset may still be normal. This first period often occurs later in the developing world
Centre for Menstrual Cycle and Ovulation Research Centre for Menstrual Cycle and Ovulation Research The Centre for Menstrual Cycle and Ovulation Research (CeMCOR) is a health research centre in Vancouver. According to the University of British Columbia, CeMCOR is the only centre in the world that focuses on ovulation and the causes and consequences of ovulation disturbances. CeMCOR is known for research on progesterone-only therapy for menopausal hot flushes, research on perimenopause as distinct from menopause, and for a focus on women's perspectives and self-knowledge. The Centre was founded by Dr. Jerilynn Prior in May 2002 as a charity affiliated with the University of British Columbia. The