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15 Unexpected Reasons You May Have Missed Your Period

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Last updated April 24, 2024

Missing period quiz

Take a quiz to find out what's causing your missing period.

You know you’re not pregnant, so what is the reason? Missed, irregular, or late periods can happen for many reasons. Read on for some causes of missed periods.

Missing period quiz

Take a quiz to find out what's causing your missing period.

Take missing period quiz

You’ve learned to count on certain things — it’s comforting when you know what to expect and when. Like your period. And when it doesn’t happen when you know it should, the worrisome wait begins. Days pass, and still nothing. Missed, irregular, or late periods can happen for a variety of reasons. Read on for some of the most common causes of missed periods.

Initial years of menstruation

Menstrual cycles vary from woman to woman. Flow may occur every 21 to 35 days and last for 2 to 7 days. During the first few years of menstruation, cycles tend to be irregular and long cycles are common. However, within a few years, menstrual cycles tend to even out and become more regular.


Stress can have a number of impacts on your health. Enough stress can temporarily change how the part of your brain (hypothalamus) that controls the hormones regulating your menstrual cycle works. You can miss one period, then another, and another. Stress reduction techniques, lifestyle changes, and exercise can help reduce stress and the effects it has on your menstrual cycle. When the stress is decreased, your regular cycle resumes. If you are having difficulty managing stress and feel overwhelmed, it’s best to consult your doctor.

Excessive exercise

Although exercise is good for the body and mind, sometimes it’s a case of too much of a good thing. Sports or activities that require long hours of intense training — marathons, ballet, or gymnastics — can cause missed periods by affecting the normal production and balance of the hormones that regulate your menstrual cycle.

Low body weight

Excessive weight loss that results in approximately 10 percent under normal weight guidelines can affect hormone function similar to how excessive exercise does. Ovulation and menstruation stop. Eating disorders, such as anorexia nervosa or bulimia, can cause such low body weight that missed periods become the norm. Medical consultation and therapy can address the underlying eating disorder. Once proper body weight is achieved and maintained, normal hormonal function should resume.


Most women who breastfeed experience a delay in the return of regular menstrual cycles following pregnancy. However, if your periods return and then stop after you end breastfeeding, check in with your doctor.


Perimenopause, which literally translates to "time around menopause", marks the body’s natural transition phase to menopause. It can start at different ages and last for a varying number of years. It usually occurs after age 40, but some women experience it as early as their 30s. Menstrual cycle changes can occur in response to fluctuating estrogen levels. These include missed periods, irregular periods, and changes in flow. Menopausal symptoms — such as hot flashes, vaginal dryness, or sleep or mood changes — also may occur. A visit to your doctor and subsequent testing can confirm if you are in perimenopause.


Just as low body weight can affect hormone function leading to missed periods, so too can excessively high body weight or obesity. Lifestyle changes, including exercise and a healthy diet, can lead to weight loss and a resumption of a regular menstrual cycle. Your doctor can help you to devise a plan tailored to your needs.


A few types of medications can affect the menstrual cycle and cause missed periods. These include antidepressants, antipsychotics, and some allergy, chemotherapy, or anti-hypertension drugs. It’s a good idea to alert your doctor if you’re on a new medication and experience a missed period.


Diabetes occurs when your body fails to produce or respond to the hormone insulin. This is a major problem as insulin is essential for the necessary transport of glucose to your body cells, which they use for energy. Excess glucose can damage your blood, increasing your risk for serious complications. Diabetes can affect the menstrual cycle through the interaction of insulin and estrogen and progesterone, the hormones that control menstruation. The result can be missed periods. If your missed periods have been accompanied by any of the symptoms of diabetes, such as increased thirst, hunger, or urination, fatigue, unexplained weight loss, slow-healing wounds, blurred vision or frequent infections, consult with your doctor.

Celiac disease

If you have celiac disease, consuming gluten, a protein found in wheat, barley and rye, triggers an immune response in your small intestine. This causes a malabsorption of essential nutrients. Although most closely associated with gastrointestinal symptoms, celiac disease can cause changes in many body systems, including the menstrual cycle. Missed periods can be one of these changes. If you’re experiencing diarrhea, fatigue, weight loss, or bloating in addition to an inexplicably missed period, it’s wise to check with your doctor regarding the possibility that you may have celiac disease. Although there is no cure, a gluten-free diet can do much to keep the disease at bay and minimize possible complications.

Thyroid malfunction

The thyroid gland, located at the base of the neck, controls many of the body’s activities through its production of thyroid hormone. Too much thyroid hormone, or hyperthyroidism, can cause you to miss periods. Your doctor can check your thyroid function through blood tests to determine if this may be the reason for your missed periods.

Polycystic ovary syndrome

Exactly why PCOS occurs remains unknown. Heredity, excess insulin production, low-grade inflammation, or excess androgen production all may be factors in its development. If you have PCOS, you can experience a missed period due to high and sustained hormone levels instead of the cyclic hormonal levels seen in a normal menstrual cycle. You may have PCOS if you have missed periods along with excess facial or body hair, severe acne, weight gain, or loss/thinning of hair on your head. If you suspect that your missed period may be related to PCOS, consult your doctor so investigative tests can be done.

Premature ovarian failure

Premature ovarian failure or primary ovarian insufficiency occurs when there is a loss of normal ovarian function before age 40. When this happens, normal amounts of estrogen fail to produce, and ovulation becomes irregular. Missed periods are the result. There are other effects as well, including infertility and osteoporosis. If you’re under age 40, it’s best to check with your doctor to rule out this cause of your missed periods.

Pituitary tumor

The pituitary gland is found at the base of the brain, right behind the eyes. It’s often called the "master gland" that regulates the body’s hormones. Pituitary tumors, which are noncancerous, may or may not cause symptoms, including the loss of regular periods due to overproduction of the hormone, prolactin. Medication can often help resolve the effects of pituitary tumors. Contact your doctor to learn about treatment options.

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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