If you plan on having kids some day, or simply want to have better health and regular periods, definitely have yourself checked for polycystic ovary syndrome. "PCOS ... is an endocrine disorder that causes an alteration of sex hormones in the female body," says Elizabeth Shaw, MS, RDN, CLT, co-author of Fertility Foods. "PCOS affects 5 to 10 percent of reproductive age women and is considered the primary cause of ovulatory infertility." And because it can cause women to experience alternations in hormones, one of the main signs is an irregular periods.

If you miss your period, and have intense abdominal pain, dizziness, and nausea, there's a chance you could have an ectopic pregnancy, which is when the fertilized egg implants in your fallopian tube, instead of your uterus.

"If you miss a period and have an irregular period, you really want to think about taking a pregnancy test," Dr. Prudence Hall, author of Radiant Again & Forever, tells Bustle. "Women can have an ectopic pregnancy [and it can be] hard to diagnose it, because many times, the [pregnancy] test will come out negative." And since an ectopic pregnancy can rupture, you definitely want to seek medical care ASAP.

Endometriosis is a disorder where tissue that normally lines the inside of your uterus starts growing outside your uterus. Hall says this is cause for concern not only due to the potential for extremely painful periods, because it can lead to fertility problems down the road. If it turns out you have it, there are treatments available, such hormone therapy, that can help get things back on track.

"POF occurs when your ovaries stop functioning the way they should before the age of 40, meaning they don’t produce eggs as they should and ovulation falters or fails to happen completely," Nicole Jardim, a women's health coach and professional period fixer, tells Bustle.

When it comes to tumors and cancer, it's important not to self-diagnose or jump to conclusions. But if you have irregular periods — plus a few other symptoms — it might be something worth considering.

"The pituitary gland, which is located at the base of the brain, helps to regular many of the body's hormone levels," Dr. Nina Watson, a board-certified diagnostic radiologist, specializing in women's imaging, tells Bustle. "Tumors of this gland can cause irregular or absent periods and vision changes, such as double vision. If a woman is experiencing these, she should see her doctor right away."

Even though exercise is great for you, it is possible to have too much of a good thing. "The body needs a certain amount of fat (which varies for each individual) to menstruate, and by not supplying this, the body can lose its regular cycle," Shaw says.

While not everyone who exercises intensely should be concerned, you might want to talk with a doctor or therapist if you're also restricting your eating — which is another habit that can lead to irregular periods. "The best way to combat this is to work with your health care team to restore menses through nutrition and dietary modifications," Shaw says.

Since so many irregular periods are due to hormonal issues, it might be worth getting your thyroid checked. "Thyroid disease is the number one reason we see irregular cycles," Powers says. "The most common being hypothyroid, which causes exaggerated PMS symptoms and long, heavy periods with painful cramps."

But if your periods are short, it could be due to hyperthyroid. "This can cause very short, light periods, or no period at all," Powers says. "A lot of thyroid conditions have an underlying autoimmune cause. It is very important that women ask for their thyroid antibodies to be checked when they receive a routine evaluation at their OB/GYN."

If you have irregular periods, your doctor will likely check you for uterine polyps. A polyp is an overgrowth of the uterine lining (endometrium) that's almost always benign, fertility expert Mark P. Trolice, MD tells Bustle. They are worth worrying about, and treating, though, since they can lead to a super heavy flow during your period, fertility issues, and sometimes even miscarriage.

Irregular menses could also be due to diabetes, urogynecologist Dr. Neeraj Kohli tells Bustle. While it's rare for this condition to affect your period, it can happen and you should check with your doctor if you think this may be occurring with you.

Sexually transmitted diseases can mess with your period, too, Kohli tells Bustle. If you've been getting your period more frequently, for example, it could be due to the likes of chlamydia or gonorrhea, which are known to cause inflammation in the uterus, according to MedicineNet.com.

In rare cases, an irregular period could be due to cancer of the cervix, endometrium, or uterine body, which can first show itself through abnormal bleeding, Trolice tells me. Again, don't jump to conclusions. But it's always important to be your own health advocate, and follow up with your doctor if you are worried.

If your period is suddenly different than what's been normal for you over the years, take note. Missed or irregular periods could be due to a bout of stress, or recent travel. Or it could be due to something a little more serious. If you have irregular periods, along with other symptoms and you're worried, talk to your gynecologist ASAP.