Pms Basics

What is a Menstrual Cycle?

A woman’s body usually prepares for pregnancy about every 28 days. Each woman’s body is unique but, in general, the menstrual cycle is considered to begin on the first day of bleeding and continue to the first day of the next period. For some women, a menstrual cycle is as short as 23 days or as long as 35 days; for some women, each month may be different from the last. What one woman might consider an irregular menstrual cycle might be normal for another woman.

About mid-cycle, a woman’s body releases an egg from the ovaries down the fallopian tubes and towards the uterus. The lining of the uterus prepares for pregnancy by thickening. If the egg remains unfertilized (if no sperm reaches it), the extra blood and tissue that formed in the uterus is shedding this is what women call their “period.” Then a new menstrual cycle begins.

More About Periods

Somewhere between the ages of eight and 16, most girls in the United States begin menstruation. The average age is about twelve, but this average has been getting younger in recent years. The beginning of a girl’s first menstrual cycle is called menarche.

Menstrual periods may last from three to seven days or, in some cases, even longer. Some women have an irregular menstrual cycle for several years; others are as regular as rain from menarche to menopause.

Keeping a Menstruation Calendar

Maintaining a menstrual cycle journal or menstruation calendar will help you determine the length of your cycle. Each month, mark the first day of your period. After several months, count the days between periods and calculate the length of your cycle. Knowing when to expect your period can help you prepare: eat right, exercise regularly and keep sanitary supplies handy when your period approaches.

Irregular Menstrual Cycles

The vast majority of women experience some degree of irregularity in their menstrual cycle. The four types of menstrual irregularities are:

  • Amenorrhea: absence of periods
  • Dysmenorrhea: severe menstrual cramping
  • Menorrhagia: excessive menstrual bleeding
  • Oligomenorrhea: infrequent menstruation.

Premenstrual Disorders

Women regularly suffer from more than 150 premenstrual and menstrual discomforts, ranging from water retention and breast tenderness to severe cramping and migraine headaches. Feeling just plain grumpy and experiencing mood swings is also part of the gamut of PMS symptoms.

But these symptoms should not be confused with premenstrual dysphoric disorder, or PMDD, a major premenstrual mood disturbance that affects three to eight percent of women.


Facts for Health Staff. (n.d.) Premenstrual dysphoric disorder. Retrieved September 18th, 2009, from the Facts for Health Web site:

Mayo Clinic Staff. (n.d.) Premenstrual syndrome (PMS). Retrieved September 18th, 2009, from the Mayo Clinic Web site:

Women’s Health Staff. (n.d.) Menstruation and the menstrual cycle. Retrieved September 18th, 2009, from the Women’s Health Web site: