Every month or so, the uterus lining gets thicker to prepare for a fertilized egg if the woman becomes pregnant. If the egg doesn't get fertilized, that lining is released from the body as blood through the vagina. This monthly process is called menstruation or a period.
The menstrual cycle. Hormones are released by the pituitary gland in the brain to stimulate the ovaries during the reproductive cycle. ... The period consists of a small amount of blood and the endometrium. The bleeding is caused by the breaking of fine blood vessels within the womb as the lining detaches itself.Dec 12, 2016