Menstruation

Menstruation, also known as a period or monthly, is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. Up to 80% of women report having some symptoms prior to menstruation. Common symptoms include acne, tender breasts, bloating, feeling tired, irritability, and mood changes. These symptoms interfere with normal life, and therefore qualify as premenstrual syndrome, in 20 to 30% of women. In 3 to 8%, symptoms are severe.

The first period usually begins between twelve and fifteen years of age, a point in time known as menarche. However, periods may occasionally start as young as eight years old and still be considered normal. The average age of the first period is generally later in the developing world and earlier in developed world. The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women and 21 to 31 days in adults (an average of 28 days). Menstruation stops occurring after menopause which usually occurs between 45 and 55 years of age. Bleeding usually lasts around 2 to 7 days.