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Things to Know About Your Period

Did You Know?


Updated May 30, 2014

  • Periods can vary greatly from woman to woman and from month to month and still be normal. Generally, the length of your menstrual cycle can fluctuate from 3 weeks to 5 weeks, without alarm.

  • When counting the days in your cycle, always count the first day of your period as day one. The average period lasts about 6 days, although some women may experience slightly shorter or longer periods and be perfectly normal.

  • Variations in the amount of menstrual flow and the timing of menstruation are quite normal in young women during the first few years following the onset of menstruation. Periods may be irregular or very light. The use of oral contraceptives can often cause fluctuations in menstruation which include either light periods or spotting/bleeding between periods.

  • It is not uncommon for young women to feel frightened when dark clumps of tissue is discovered in their menstruation. However, this is usually nothing abnormal and just a part of the endometrium, or uterine lining that is shedding.

  • The average age of the onset of menstruation is about 12 or 13, however it may begin as young as 8 for some girls or not until 14 or 15 for others. If your period has not started by the time you are 16, see your physician to determine whether there may be an underlying condition.


Menstruation. ACOG Education Pamphlet AP049.http://www.acog.org/publications/patient_education/bp049.cfm. Accessed 08/26/09.

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