During the menstrual cycle, the female body prepares to nurture a fertilized egg by increasing hormone production and thickening the lining of the uterus, states WebMD. Monthly bleeding occurs when an egg is not fertilized for pregnancy, and the body automatically sheds the excess tissue from the uterus.Continue Reading
The first menstruation period usually starts between ages 8 and 15, according to MedicineNet. Depending on the individual, a complete cycle lasts 21 to 45 days in teen girls and 21 to 35 days in adult women. The flow of menstrual blood from the body is considered the beginning of the cycle. In the following days, the body produces high amounts of the hormone estrogen, which contributes to uterine thickness and bone health. Hormones also cause the ovaries to grow follicles that store eggs, and during the process of ovulation, the eggs grow until they are mature enough to travel to the uterus, or womb. Ovulation is the period when a woman is most fertile, and it starts at around day 14 of the cycle.
A mature egg passes through the fallopian tubes where it can be fertilized by a male���s sperm, explains MedicineNet. If a woman becomes pregnant, the eggs attach to the uterine lining, which delivers nutrients to the developing embryo. When a woman does not conceive, the body stops producing excess hormones at around day 25, and the unfertilized egg passes out of the body in menstrual blood.Learn more about Menstruation