I.Test Your Knowledge
II.The Phases of the
Menstrual Cycle
III.About Your Period
>Menstrual Period Q & A
IV.Symptoms Related to
Your Cycle
V.Managing Your Cycle
VI.Contraception and
Your Cycle
VII.Glossary
Chapter III:
About Your Period



Throughout a woman's life, her menstrual cycle can change at times such as menarche and perimenopause.[10. Berek, p. 159D; 20. Treloar B p 124 C ; 32. Sherman p 700A]
Maybe you’ve been getting your period for some time, or maybe the experience is brand new to you. As you get older, you may find that your period seems different than it used to be. In all cases, it’s important to remember that every woman is different. Some women have shorter, lighter periods, while others have heavier, longer periods. Any of these scenarios can be perfectly normal. And it's also normal for a woman’s menstrual cycle to change over time.Berek, p. 159 D




The Basics

Menstruation is the monthly discharge of blood and mucosal tissue from the uterus through the vagina.Dorland’s Medical Dictionary, p. 1128 Here are a few general points regarding the range of experience that women have with their periods:

    Menarche, the time of a woman’s first period, normally occurs around twelve and a half years old. [7. Dorland’s Medical Dictionary, p. 1124; 33. Chumlea p 111.]
  • A woman typically loses less than 4 tablespoons (>60 mL) of blood each month during her period.34. Hallberg,p 349, 35. Fraser, p 808

  • Most women have periods that are from 3 to 8 days in length.19. Fehring p 380 The average is 6 days.19. Fehring p 380A

  • Menarche, the time of a woman's first menstrual period, normally occurs between the ages of 12 and 13.7. Dorland’s Medical Dictionary, p. 1124; 33. Chumlea p 111 By the age of 15, 98% of girls will have had their first periods.36. National Center for Health Statistics p 3; 37. ACOG No 349 p. 1324B

  • A woman gets her period roughly every 4 weeks from the time she has her first period (menarche) until menstruation stops (menopause).36. National Center for Health Statistics p 3; 37. ACOG No 349 p. 1324B

  • The lengths of a woman's menstrual cycles vary the most during the few years right after menarche (first period) and in the years right before menopause. 20. Treloar B p 124 C, 10. Berek p 159D

Learn more about the range of experiences women can have with their periods in the menstrual period Q&A.

It's important to make the distinction between a period and breakthrough bleeding because many women believe they are the same. Breakthrough bleeding, also known as intermenstrual bleeding, is a term that describes bleeding between periods.10. Berek, p. 159A Some women on oral contraceptives may experience breakthrough bleeding.38. Gallo pp 6-8 The good news is that there are various options you can discuss with your health care provider to get the bleeding under control, such as changing to a different birth control pill.4. Danforth's Obstetrics & Gynecology, p. 650 For some women, uncommon yet important causes of breakthrough bleeding between periods can include hormonal disorders, infection, and cancer.Danforth's Obstetrics & Gynecology, p. 643-647A-G; ACOG. Abnormal Uterine Bleeding. p 3B Talk to your health care professional if you're concerned about breakthrough bleeding.

Your period is just one part of your monthly cycle. Learn more about the phases of the menstrual cycle.