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.