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10 Causes of Irregular Periods

Wondering Why Your Period's Irregular?

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If your period changed, became heavier, lighter, longer, or less frequent, would you notice? Paying attention to irregularities in your cycle provides a clue into your overall health. While some issues, such as stress, may temporarily affect your period and resolve on their own, others can indicate a more serious health problem that needs to be addressed.

"I always recommend patients download a period tracker app on their phone," says Eduardo Lara-Torre, M.D., an ob-gyn at Carilion Clinic in Virginia. "It's important to understand what's normal for you so you can identify when something isn't right." Take a look at these common causes of irregular periods, so you can begin tracking your cycle's changes―addressing these menstrual changes early on can prevent them from getting worse so you can sail smoothly through your monthly flow. (Read why period tracking apps are great, straight from women who do it every month.)

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A Serious Stressor

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You've heard that stress can mess with your cycle. But although they're not exactly good for you, daily hassles (you know: commuting, deadlines, presentations) are unlikely to impact your period. "It often takes a one-time extraordinarily stressful event to create an abnormal period," Dr. Lara-Torre says. Think: Death of a family member, loss of your job, divorce, or illness. There may be an evolutionary explanation behind this phenomenon: When you're focused on survival (whether the threat is a saber-tooth tiger or paying your mortgage) your body and brain shut down the hormones needed to make your body ovulate in order to prevent reproduction in a threatening environment, Dr. Lara-Torre says. (FYI, stress can mess with your skin too.)

 

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Excess Exercise

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Working out for hours a day may put your periods on hold. Your body perceives excess exercise as an extreme stressor and may put the kibosh on the monthly hormonal symphony it's used to producing. "You need a certain amount of body fat to ovulate, so if your body fat dips too low you may stop ovulating," says Mary Jane Minkin, M.D., professor of obstetrics and gynecology at Yale School of Medicine. (Also see: 9 Good Reasons to Skip Your Workout) You may notice you don't get your period at all or you get it a few times per year on an unpredictable schedule. However, research has shown that a healthy amount of exercise during your period can actually boost strength and muscle mass. ​

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Alcohol

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A few boozy nights out could leave you with more lasting effects than a string of killer hangovers. According to the National Institute on Alcohol Abuse and Alcoholism, drinking, even in amounts that won't cause damage to your liver or other organs, can cause irregular periods. Alcohol may temporarily increase levels of estrogen and testosterone, which may disrupt the normal hormonal fluctuations necessary for ovulation. As a result, your periods may become irregular or you may even skip them. Researchers aren't sure how much alcohol it takes to disrupt your cycle—the quantity likely varies from woman to woman, but sticking to the guideline of one drink or less per day is the best way to keep your pinot from interfering with your period.

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Weight Gain or Loss

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Rapid weight gain, such as packing on 50 pounds over the course of a few months, can throw your hormones for a loop. "With weight gain, your ovaries start producing extra testosterone," Dr. Minkin says. "This can prevent ovulation, so you may have very long cycles or skip your period altogether." By the same token, extreme weight loss, especially as a result of an eating disorder like anorexia or bulimia, also messes with your hormones and can even stop your periods altogether. 

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Infections

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An infection won't impact your cycle on a hormonal level, but it can cause bleeding and make you think you're getting your period more frequently than normal. "Bacterial infections, pelvic inflammatory disease, and sexually transmitted infections can cause the inside of your uterus to become inflamed and bleed," Dr. Lara-Torre says. "You'll still get your regular period, but you may bleed in between because of the infection." You may even experience cramping because the uterus perceives bleeding as an irritant. If the bleeding seems random and you experience any other signs of an infection such as painful urination, pain or tenderness in your abdomen, pain or itching in your vagina, unusual discharge, fever, or vomiting, pay a visit to your gyno.​ (Next up: 7 Conversations You Must Have for a Healthy Sex Life)

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Antidepressants or Other Prescription Drugs

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Antidepressants and other medications can disrupt your cycle and cause you to skip periods or get them more frequently. "Many of these medications elevate a pituitary hormone called prolactin, which can alter other hormones in your body that regulate your cycle," Dr. Minkin says.

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Shift Work

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In a study of 119,000 women, researchers found that those working evenings and nights had a 33 percent higher risk of menstrual problems such as irregular periods and fluctuations in how long they lasted. The more your work schedule fluctuates, the more likely you are to experience problematic periods. One study found that women who worked rotating shifts were 23 percent more likely to have very short cycles (less than 21 days) or very long ones (40 days or more) than those who followed a more set schedule (even if they worked nights), the journal Epidemiology reports. One explanation is that shift work disrupts your body's circadian rhythm, which controls a variety of biological functions—including your menstrual cycle.

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Thyroid Disorder

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Irregularity in your cycle can be signs of an issue with your thyroid, especially amenorrhea, a condition where periods stop for several months at a time. Research shows that either overproductivity or underproductivity of the thyroid gland is strongly correlated with menstrual problems, because the thyroid helps regulate the body's hormone production. Check with your doctor if you're seeing the red flag of a missed period, or if you have a family history of thyroid conditions. 

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Smoking

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Women who smoke experience much worse PMS than women who don't, according to researchers at the University of Massachusetts in Amherst. Your risk of developing PMS climbs the more you smoke and the younger you were when you first started puffing. According to researchers, smoking may alter levels of estrogen, progesterone, testosterone, and other hormones involved in the development of PMS. Women who smoke also have shorter and more irregular menstrual cycles than non-smokers.

The good news: You can actually use your menstrual cycle to help you quit. Recent research found that the decrease in estrogen from days 14 through 28 of your cycle (after ovulation and before your period arrives) can help keep withdrawal symptoms at bay so you can power through quitting.

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PCOS

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Do you have long, unpredictable, or MIA periods? Polycystic ovary syndrome (PCOS) may be to blame. The condition affects as many as 10 percent of women of childbearing age. PCOS is a hormonal imbalance in which the ovaries produce too much testosterone, which blocks ovulation. "When you don't ovulate, you don't get the release of progesterone, which causes you to get your period," Dr. Minkin says. PCOS is the most common cause of infertility in women.

Here's the thing: Even if you had regular periods before, for unknown reasons you may spontaneously develop PCOS. In addition to long and irregular periods, other signs of PCOS include acne, excessive hair growth, and weight gain. While birth control pills can help regulate your cycle, PCOS is associated with other serious health conditions such as obesity, diabetes, high blood pressure, heart disease, and more. Discuss your symptoms with your doctor if you think you might have PCOS

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