Share this Story

Irregular Periods Explained: 8 Big Reasons Your Period's Gone MIA

Sarah Kelsey is a lifestyle writer, editor and spokesperson based in Toronto. She was the editor of AOL/The Huffington Post Canada’s StyleList, Style and Living sites. Today, she's a freelancer writing for some of North America’s top pub...

Missed periods are more than just an annoyance — your body is actually trying to tell you something

If you've fallen victim to irregular periods, then we don't have to tell you that they suck big time. When they're missing, your mind starts racing with the whole, "am I pregnant?" internal dialogue — and it's also not super fun when all of the sudden you start bleeding without any prior warning.

Yes, erratic menstrual patterns are annoying and stressful, but they're not totally useless. If you pay close attention to your cycle, you'll actually find that your body is trying to communicate with you — and irregular periods are a big sign that something isn't right.

That doesn't mean you need to panic, though. The good news is that once you've ruled out any potential medical issues, you can attempt to figure out the underlying cause of your missing cycle.

A normal period versus an irregular period

"The monthly menstrual cycle typically occurs every 28 days, is controlled by various hormones and is a key function of the female body," says Dr. Sherry Ross, MD, OB/GYN and Women’s Health Expert at Providence Saint John’s Health Center in Santa Monica, California. "Your 'period' begins around 11-12 years of age, lasts 2-7 days and continues until your reach menopause, which occurs around 51 years old."

Ross continues: "Ovulation is an important part of the menstrual cycle and occurs around Day 14 when an ovarian follicle produces an egg, which can be fertilized by sperm. The egg is only available to be fertilized for 24 hours before it disintegrates. Once you have ovulated, your period will occur, which is typically 14 days later."

The amount of blood shed during a period varies from person to person. Some people who menstruate routinely have heavier periods (losing up to 12 teaspoons of blood each month) while others may experience a period that's almost non-existent (losing as little as four teaspoons of blood).

More: The Most Common Vaginal Infection Isn't What You Think

If you've been menstruating for a while, your body will get into a period flow, which is why an irregular period is usually defined as any type of bleeding that's abnormal when compared to your last few menstrual cycles. It can include everything from a late period to early bleeding, and scant bleeding to extremely heaving bleeding. For many individuals, this can even mean an absent period (amenorrhea) or two periods in one month (metrorrhagia). Two periods in one month, or a period every two weeks, are thought to be caused by an imbalance in estrogen and progesterone and may require a trip to the doctor since this can induce anemia.

And if you're not prone to PMS, you can also consider a period irregular if you experience heavy cramping and bloating or headaches.

The many causes of irregular periods

Every person who menstruates will experience an irregular period from time-to-time, and though, in most cases, they aren't dangerous, it's important to figure out what's causing the irregularity. Here are a few common reasons you may be experiencing an abnormal flow.

1. Stress

Missed periods are more than just an annoyance — your body is actually trying to tell you something
Image: Film Magic/Film Magic/Getty

Stress is the most common cause of irregular periods. Cortisol, the stress hormone, has a direct impact on how much estrogen and progesterone, two sex hormones, gets produced by the body. If you have too much cortisol in your bloodstream, the time and flow of your cycle could change.

Dr. Carolyn C. Thompson, MD, FACOG, board-certified OB/GYN, explains that in order for a woman to have a normal menstrual cycle (in which she does not become pregnant), the hypothalamus in the brain must send hormonal signals to the pituitary gland, which must in turn signal the ovary, which then signals the uterus.

In case you need an anatomy refresher, the hypothalamus is adjacent to areas in the brain that influence emotion; neurotransmitters form these centers can shut down the signals to the hypothalamus and therefore stop the outgoing signals from the hypothalamus.

"Evolutionarily speaking, this makes sense — if a woman is under a great deal of stress, either physical or emotional, it is likely not an ideal time for a pregnancy, so the system shuts down," Thompson adds.

More: A Quick (but Important) Introduction to Pelvic Inflammatory Disease

2. Diet

Missed periods are more than just an annoyance — your body is actually trying to tell you something
Image: Digital Vision/Getty Images

Another common reason for a late or missing period is the food you eat and, more specifically, the weight you're carrying. If you're eating a diet that's rich in unhealthy carbs or if you've gained weight, your body will produce varying levels of certain hormones, shifting when you ovulate.

The same goes for people who menstruate as they lose weight. "In order for a woman to maintain a regular cycle, her body fat percentage needs to be at least 17-22 percent. This is again related to the evolutionary idea that a state of starvation is not conducive to maintaining a healthy pregnancy, so, again, the system shuts down," says Thompson.

3. Exercise

Missed periods are more than just an annoyance — your body is actually trying to tell you something
Image: John Fedele/Blend Images/Getty

Our bodies need energy to menstruate. If you're burning too much of your energy in the gym, there will be nothing left for your body to use during that time of the month.

"The list of what causes irregular periods is longer than you think, but we know excessive exercising, sudden weight changes and being underweight can offset your hormone levels. One of these hormones is called Leptin and is produced in fatty tissue. Excessive exercising and drastic weight changes can decrease the body fat, causing this and other hormones to drop, contributing to irregular periods," says Ross.

4. Birth control pills

Missed periods are more than just an annoyance — your body is actually trying to tell you something
Image: Jamie Grill/Getty Images

It can take several months for your body to get used to the dose of hormones birth control pills deliver. On top of that, Ross explains that one of the side effects of a low dose birth control pill is a light or non-existent period.

For some, this is a welcomed side effect. When a menstruating person stops taking the pill, their periods may take one to three months to return to normal.

"The birth control pill doesn’t cause you to have amenorrhea," Ross says. "It may be once you are off the pill you may find you have an underlying hormonal problem that was masked by taking the birth control pill. If this is the case, you should alert your healthcare provider."

Next Up: Polycystic ovary syndrome (PCOS)

Originally published January 2016. Updated June 2017.

1 of 2
Follow Us

SheKnows Media ‐ Beauty and Style

New in Health & Wellness

And you'll see personalized content just for you whenever you click the My Feed .

SheKnows is making some changes!

b h e a r d !

Welcome to the new SheKnows Community,

where you can share your stories, ideas

and CONNECT with millions of women.

Get Started