Menstrual irregularities

Do you know when your last period began or how long it lasted? If not, it might be time to start paying attention.

Around 14- 25% of women have irregular menstrual cycles, which means the cycles are shorter or longer than normal, heavier or lighter than normal, or accompanied by other health issues, like abdominal cramps1

The menstrual cycle – definition, features and duration

Before dealing with irregularities in the menstrual cycle, you need to understand what a cycle is. The menstrual cycle is the monthly series of changes in a woman’s body to prepare for a possible pregnancy. Each month, one of the ovaries releases an egg, a process called ovulation. At the same time, hormonal changes prepare the uterus for pregnancy. If ovulation occurs and the egg isn’t fertilized, the uterus lining sheds through the vagina. This is a menstrual period2.

The menstrual cycle, which is counted from the first day of one period to the first day of the next, isn’t the same for every woman. Menstrual flow might occur every 21 to 35 days and last two to seven days. For the first few years after menstruation begins, long cycles are typical. However, menstrual cycles tend to shorten and become more regular as you age2.

Your menstrual cycle might be regular — about the same length every month — or somewhat irregular. Your period might be light or heavy, painful or pain-free, long or short, and yet still be considered normal. Within a broad range, “normal” is what’s normal for you2.

Keep in mind that using certain types of contraception, such as extended-cycle birth control pills and intrauterine devices, will alter your menstrual cycle2

How to detect menstrual irregularities?

The most common menstrual irregularities include1:

  • Amenorrhea or absent menstrual periods. When a woman does not get her period by age 16, or when she stops getting her period for at least 3 months and is not pregnant
  • Oligomenorrhea or infrequent menstrual periods. Periods that occur more than 35 days apart
  • Menorrhagia or heavy menstrual periods: Also called excessive bleeding. However, anovulatory bleeding and menorrhagia are sometimes grouped. They do not have the same cause and require different diagnostic testing
  • Prolonged menstrual bleeding. Bleeding that exceeds 8 days duration on a regular basis
  • Dysmenorrhea: Painful periods that may include severe menstrual cramps

Additional menstrual irregularities include1:

  • Polymenorrhea: Frequent menstrual periods occurring less than 21 days apart
  • Irregular menstrual periods with a cycle-to-cycle variation of more than 20 days
  • Shortened menstrual bleeding of fewer than 2 days duration
  • Intermenstrual bleeding: Episodes of bleeding that occur between periods, also known as spotting

What causes menstrual cycle irregularities?

Menstrual cycle irregularities can have many different causes, including2:

  • Pregnancy or breastfeeding. A missed period can be an early sign of pregnancy. Breastfeeding typically delays the return of menstruation after pregnancy
  • Eating disorders, extreme weight loss or excessive exercising. Eating disorders — such as anorexia nervosa — severe weight loss, and increased physical activity can disrupt menstruation
  • Polycystic ovary syndrome. Women with this common endocrine system disorder may have irregular periods and enlarged ovaries. It contains small collections of fluid — called follicles — located in each ovary, as seen during an ultrasound exam
  • Premature ovarian failure. Premature ovarian failure is the loss of normal ovarian function before age 40. Women with premature ovarian failure — also known as primary ovarian insufficiency — might have irregular or occasional periods for years
  • Pelvic inflammatory disease. This infection of the reproductive organs can cause irregular menstrual bleeding
  • Uterine fibroids. Uterine fibroids are noncancerous growths of the uterus. They can cause heavy and prolonged menstrual periods

What can I do to prevent menstrual irregularities?

For some women, the use of hormone therapy can help regulate their menstrual cycles. Treatment of irregular menstruation is individual for each woman. Therefore, if you have signs of menstrual irregularities, consult your doctor, who will determine the necessary therapy2.  

In addition, consult your health care provider if2:

  • Your periods suddenly stop for more than 90 days — and you are not pregnant
  • Your periods become erratic after having been regular
  • You bleed for more than seven days
  • You bleed more heavily than usual or soak through more than one pad or tampon every hour or two
  • Your periods are less than 21 days or more than 35 days apart
  • You bleed between periods
  • You develop severe pain during your period
  • You suddenly get a fever and feel sick after using tampons

Talk to your health care provider if you have questions or concerns about your menstrual cycle.


  1. What are menstrual irregularities? (Last access 15.06.2022). 
  2. Menstrual cycle: What’s normal, what’s not. (Last access 15.06.2022).