While most women aren’t exactly excited about menstruation, most realize the importance of this bleeding when, suddenly, one month it either doesn’t appear or it shows up when least expected. What’s going on when you have irregular periods? Or why do they suddenly stop?  Let’s start by understanding the mechanics of the menstrual cycle.

During a woman's fertile life, the eggs mature within the ovaries in a cycle that typically lasts 28 days (this varies from woman to woman and even from period to period). On day five of the cycle, about twenty eggs start to mature in the follicles of the ovaries.  Each of these follicles is like a tiny fluid-filled sac.  As day fourteen approaches, one follicle has generally matured earlier than the others and releases its mature egg to be fertilized.  What happens to the other follicles? They shrivel up and are reabsorbed by the body.  But the mature follicle transforms into what is known as a "corpus luteum," which is responsible for producing the hormone progesterone to prepare the uterus to receive the fertilized egg.

If the egg is not fertilized, it disintegrates and dies. Likewise, the corpus luteum withers.  This causes the uterus to shed its lining, the endometrium, causing the bleeding of menstruation.

• What is a regular menstrual cycle? Having a regular cycle means that the interval between periods is consistent. As mentioned earlier, it’s usually 28 days, but depending on the individual woman, can range from every 20 to every 35 days.
• What is an irregular menstrual cycle? Having an irregular cycle means that the interval between periods varies each month. That is, sometimes they come every 28 days, sometimes every 20, sometimes every 30.

Having irregular periods is very common. I see them in my practice all the time. The causes can range from something insignificant to something that requires treatment. For example, if you're a teen, your body's hormones can fluctuate and take some time until they find a balance. Therefore, it’s normal to have an irregular period during adolescence or, sometimes, for your period not to arrive in a given month.

But, before we get down to business, remember that the main cause for your period not to arrive is a pregnancy. So, if your period doesn’t arrive, check to make sure it’s not actually a baby on the way.

Now, let’s look at the most common causes of irregular periods:

• Eating disorders, like anorexia and bulimia
• Excessive weight gain or weight loss; extreme thinness and obesity both cause your menstrual cycle to become irregular or even to disappear
• Stress or emotional problems
• Hormonal problems, for example, when the thyroid malfunctions
• Travel
• Over-exercising: If you're an athlete and train very hard, you may stop menstruating because your body wants to survive and save energy and menstruation requires energy
• Problems with the pelvic organs (such as polycystic ovarian syndrome, for example)
• Drugs like birth-control pills can affect the frequency and / or intensity of menstruation
• Breastfeeding

Irregular periods or a stop of menstruation can be due to a condition called "premature ovarian failure" which causes a woman to stop having her period before age 40. This can be caused by radiation, surgery or chemotherapy, in the case of a woman with cancer.

Don’t forget that if you are sexually active and don’t want to get pregnant, you should use a birth control method you can trust so that irregular periods don’t bring you an unexpected surprise. Also, remember that even if your period goes away for a while, this does not mean you cannot become pregnant. You are still at risk!  If you're not planning to have a baby, be careful!

And, as always, I recommend that you consult your healthcare provider if you have questions about what’s causing your irregular periods. That way you’ll be ahead of the game if it’s being caused by a serious condition that requires treatment.  Remember, your health comes first!