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What is Menstruation?


Updated June 19, 2014

Definition: Menstruation has many names -- period, monthly cycle, even Aunt Flo. Regardless of what you call it, menstruation is vaginal bleeding that occurs monthly in adolescent girls and premenopausal women.

During the monthly menstrual cycle, female sex hormones prepare the uterus to support a pregnancy. If pregnancy takes place, menstruation usually does not return until after childbirth. If pregnancy does not occur, the endometrial lining (the lining of the uterus) sheds during menstruation.

  • The first day you experience any amount of bleeding is Day 1 of the menstrual cycle.
  • While most menstrual cycles are between 28 and 30 days long, periods that come anywhere from 21 to 35 days apart are usually considered normal.
  • The amount of menstrual fluid lost during menstruation averages from 4 to 12 teaspoons for the majority of women. However, there are many variations of normal amounts of blood loss during menstruation.
  • Most periods last from 3 to 5 days. However, menstruation may last up to 7 days and still be normal.

See: When To See Your Doctor About Your Menstrual Cycle

Also Known As: period, menstrual cycle, monthly cycle, menstrual bleeding, monthly bleeding, Aunt Flo
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