Study indicates longer reproductive life span experienced by US women

As females age, their bodies typically undergo two significant changes that generally occur during adolescence and middle age. The first, known as menarche, is the time during puberty when a girl begins having monthly menstruation cycles, which often tends to range from 8-13 years of age. She enters the second change, known as menopause, 12 months following her last menstruation cycle when her ovarian function ceases, usually sometime in her 40s or 50s.