Learn about the 4 phases of the menstrual cycle , including all menstrual cycle phases and stages. Understand the menstrual phases and how they affect your body. Triggered by falling progesterone levels, menstruation (commonly referred to as a " period ") is the cyclical shedding of the lining, and is a sign that pregnancy has not occurred. Each cycle occurs in phases based on events either in the ovary (ovarian cycle ) or in the uterus (uterine cycle ). Menstruation – Definition Phases of Menstrual Cycle Menstrual Cycle Diagram Role of Hormones in Menstrual Cycle Frequently Asked Questions Menstruation – Defintion In a life cycle , a woman’s body is vulnerable to a variety of changes. The cycle of these changes occur in women every month, positively for pregnancy is called the menstrual cycle . When an ovum is unfertilized, the uterus lining sheds and leads to a haemorrhage, called menstruation. Every month, your body prepares to get pregnant. Your ovaries release an egg. Hormones rise and fall. This is your menstrual cycle . It starts on the first day of your last period and ends on the...