The menstrual cycle is the monthly series of changes the body goes through to prepare for pregnancy. Each month, one of the ovaries releases an egg. This is called ovulation. Hormonal changes at this time get the uterus ready for pregnancy. If the released egg isn't fertilized during ovulation, the lining of the uterus sheds through the vagina.

Menstruation is period bleeding, which is casually referred to as “having your period.” This happens monthly (for most females) during your fertile years, except during pregnancy. Menstruation occurs when the lining of the uterus sheds by breaking down and leaving the body as blood. Most periods last around three to seven days.

Menstruation, or period, is normal vaginal bleeding that occurs as part of a woman's monthly cycle. Every month, your body prepares for pregnancy. If no pregnancy occurs, the uterus, or womb, sheds its lining. The menstrual blood is partly blood and partly tissue from inside the uterus. It passes out of the body through the vagina.

Menstruation (pronounced men-stroo-EY-shuhn) is normal discharge of blood and tissue from the uterine lining through the vagina (see diagram) that occurs as part of a woman's monthly menstrual cycle.

The menstrual cycle is the hormonal process a woman's body goes through each month to prepare for a possible pregnancy. Regular menstrual periods in the years between puberty and menopause are usually a sign that your body is working normally. Irregular or heavy, painful periods are not normal.