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Irregular Periods can be confusing! If your period seems different, check out these reasons why it may seem off – and what to do about it.

Irregular periods can be scary, but don't worry. There are lots of reasons why your period may not show up on cue. Remember, it’s always best to talk to your doctor. In the meantime, we’ll try to help you understand some reasons why your periods may have changed and the causes of irregular periods.

Is this Common?

It’s common to have irregular periods every now and then, especially if you have just started your periods in the last few years. It takes a few years from when you begin for your periods to become regular.

Have you been having periods for many years? Your cycle may get shorter near age 35 and often gets shorter as you near menopause (around age 50). It’s also normal at that age to skip periods or for the amount you bleed to change. Make sure that you talk to your doctor to get all the details about the causes of irregular periods.

It’s important to know, too, that "irregular" is a personal word: You know your cycle well enough to know what’s normal for you, so you are the best judge.

Causes of Abnormal Menstrual Bleeding and an irregular menstrual cycle

There are a lot of things that can cause heavy bleeding or an irregular menstrual cycle, so you probably need to visit to your doctor to make sure that you’re alright.

Your doctor may start by checking for problems most common for your age. A few of the most common causes of irregular periods are:

  • Miscarriage
  • Use of some form of intrauterine device (IUD), which is a kind of contraceptive
  • Fibroids, benign tumours made up of muscular and fibrous tissue
  • Problems with blood clotting
  • Polyps, small (usually benign) growths with a stalk that protrude from a mucous membrane (yeah, sounds pretty weird to us, too!)
  • Chronic medical conditions (like thyroid problems, for example)

Unusual Bleeding

Unusual bleeding is when you bleed outside your cycle. Just like heavy bleeding and an irregular menstrual cycle, it’s a good idea to talk to your doctor about your bleeding symptoms if they just seem to come out of the blue.

Is Heavy Menstrual Bleeding Dangerous?

Any heavy bleeding can cause you to lose iron, which will leave you feeling weak and tired. Sometimes you might have dark, thick blood on your heaviest flow days, but if you don’t usually bleed heavily, or it lasts longer than usual, it’s time to head to the doctor. Heavy bleeding beyond what’s usual for you is definitely a medical issue or even an emergency. And it’s best to check out the causes of irregular periods, too.


  • ACOG Pamphlet 95 : Abnormal uterine bleeding