Menstruation
Menstruation, often called a period, is when the lining of the uterus (womb) sheds and leaves the body through the vagina. This happens because pregnancy has not occurred during that cycle.
A period is a normal part of the menstrual cycle and usually happens every 23–35 days. Bleeding typically lasts between 3 and 7 days, though this can vary.
What happens during a period?
Each month the body prepares for a possible pregnancy by thickening the womb lining. When pregnancy does not happen, hormone levels drop and the lining breaks down and is released as menstrual blood.
This blood is made up of:
Blood
Tissue from the womb lining
Cervical mucus