5 Common Reasons for a Late Period

If you've ruled out pregnancy and still have questions about a missed period, don't worry unnecessarily. There could be several reasons why you're late.
If you've ruled out pregnancy and still have questions about a missed period, don't worry unnecessarily. There could be several reasons why you're late.

To the uninformed, a missed period can only mean one thing: You're pregnant. But in reality, there are numerous reasons why your period might be late -- or missing altogether.

The 28-day menstrual cycle is closely tied to your overall well-being. And when your body is out of balance, it can adversely affect the timing of your period.


The medical term for absent menstruation is called "amenorrhea." Primary amenorrhea refers to late onset of menstruation, or not having started menstruation by the age of 16. However, the condition is quite rare, affecting less than 1 percent of girls in the United States.

Secondary amenorrhea refers to a situation where menstruation begins at the appropriate age, but later stops for more than three cycles or six months. Affecting roughly 4 percent of the general female population, secondary amenorrhea is more common, and can be caused by a host of factors.

Most of those components center on hormonal shifts caused by heightened stress -- whether physical, mental or emotional -- which in turn can prevent ovulation, the precursor of menstruation (ovulation occurs roughly 14 to 16 days before women have their period). The female reproductive system is incredibly efficient, yet remarkably complex. As a result, it's vulnerable to outside factors -- both subtle and overt -- that can interrupt your body's equilibrium.

Of course, if there's a chance that you might actually be pregnant, rule out that possibility first. Home pregnancy tests are fast, inexpensive and 97 percent accurate when the directions are followed [source: American Pregnancy Association]. If the test is negative, check with your doctor, but also consider one of the following five possibilities.

Next, we'll examine the role of stress.

1: Under Pressure

Stress is a silent menace and the primary cause of many physical ailments, not the least of which is internal clock disruption. In fact, emotional stress is the second most common cause of late or missed periods in teenagers and can play a huge role in adverse effects on the cycles of more mature women as well. Just think how problems with your love life (or home life, school or work) impact every other facet of your everyday life. It is the classic mind-body connection.

Emotional or mental anxiety can negatively affect the hypothalamus, the part of the brain that regulates hormones -- specifically gonadotropin-releasing hormone (GnRH) -- for both ovulation and menstruation, according to the National Institute of Child Health and Human Development.


If a woman's hypothalamus is impaired in any way, there's a distinct possibility her hormones won't manage ovulation properly. That can result in delayed or interrupted menstrual cycle.

One healthy option in overcoming the rigors of stress is to practice relaxation techniques, ranging from yoga to meditation.

Coming up, we'll consider a weighty question.

2: A Weighty Issue

The odds of having secondary amenorrhea increase if you're severely underweight (less than 15 to 17 percent body fat) or obese. The Centers for Disease Control and Prevention considers someone obese if that person has a body mass index (BMI), which is calculated from your height and weight, of more than 30. For example, a 5-foot-9-inch (1.75-meter) person weighing more than 203 pounds (92 kilograms) would be considered obese.

Both conditions stress your body's vital organs and, in turn, can delay or cease menstruation.


In most cases, a gradual weight gain or weight loss (depending on your condition) will typically cause the return of a normal cycle. It's critical to avoid rapid weight gain or loss, as both of these further strain your body. Women who undergo gastric bypass surgery should also be aware of the possibility of menstrual disruption.

Similarly, eating disorders such as anorexia nervosa and bulimia (binging and purging) can be the culprit in a missed or late period. However, these eating disorders can have serious consequences that go far beyond missing your period. If you suspect that you or someone you care for might suffer from either condition, consult with a medical professional.

Ready to go on the road again? Keep reading for our next reason your period could be late.

3: The Travails of Travel

Travel can throw you, and your cycle, for a loop. Just think how jetlag can leave you off-kilter for days.

Though everyone's body adapts more readily to a regular schedule, women are particularly susceptible to the upheaval that travel can wreak on a daily agenda -- and their bodies. It can throw off their sleep and eating patterns, both of which can have a negative effect on their menstrual cycles.


To make matters worse, most people don't eat properly while on the road, whether skimping on meals while traveling on business or overindulging while traveling for pleasure. Either situation, coupled with the added stress of getting acclimated to a different routine, can lead to delayed ovulation and menstruation.

Likewise, a change in work schedule (such as taking on a night shift) can have similar consequences.

Next, we'll examine the downside of exercise.

4: Excessive Exercise

File this under, "Too much of a good thing." Exercise generally has tremendous health benefits, but moderation is equally important. Overdo it, in terms of either intensity or duration, and you run the risk of putting your body under undue physical stress.

That can have consequences that go beyond repetitive strain injuries, such as shin splints or knee pain. Like mental or emotional anxiety, an unhealthy amount of physical stress forces your body to protect itself, and preventing ovulation can be a by-product of that phenomenon.


This form of secondary amenorrhea is often seen in endurance athletes, such as cross-country runners or professional cyclists (typically, their lower body-fat content also plays a role in delayed menstruation).

Coincidentally, the same condition can be experienced by women who suffer from a chronic illness that, on the surface, may not appear to be related to their menstrual cycle.

A late period could indicate other serious medical conditions. Keep reading.

5: Doctor Knows Best

Late or missed periods can also be the result of more complicated or serious medical conditions. Polycystic ovarian syndrome (an imbalance in female sex hormones such as estrogen and progesterone), thyroid disease, pituitary disease, a pituitary tumor, sexually transmitted diseases, infections, perimenopause and menopause have all been linked to menstrual cycle irregularities.

In rare cases, diseases such as diabetes, liver ailments and irritable bowel syndrome can delay or prevent menstruation. Furthermore, medications, including some birth control methods and antidepressants, can also result in lighter, less frequent or missed periods.


For women who recently stopped using birth control, their bodies may take as long as three months to acclimate and resume normal cycles.

So, in short, if you have questions about why you've missed your period and you've ruled out pregnancy, don't worry unnecessarily. Take the next step and consult your medical professional to determine the underlying cause.

We have lots more information about missed periods on the next page.

Lots More Information

Related Articles

  • 34 Menopause Symptoms. "Menstrual Irregularities." 2010. (March 24, 2011)http://www.34-menopause-symptoms.com/irregular-periods/articles/menstrual-irregularities.htm
  • American Pregnancy Association. "Taking a Pregnancy Test." February 2011. (April 11, 2011).http://www.americanpregnancy.org/gettingpregnant/takingapregnancytest.html
  • Centers for Disease Control and Prevention. "Healthy Weight -- it's not a diet, it's a lifestyle!" Feb. 15, 2011. (March 30, 2011)http://www.cdc.gov/healthyweight/assessing/bmi/index.html
  • Chandran, Latha. "Menstruation Disorders." WebMD. June 10, 2009 (March 25, 2011)http://emedicine.medscape.com/article/953945-overview
  • Epigee. "Menstrual Cycle Disturbances: Why is My Period Late?" (March 30, 2011)http://www.epigee.org/health/lateperiod.html Feminist Women's Health Center. "Menstrual Cycles: What Really Happens in those 28 Days?!" Jan. 21, 2011. (March 30, 2011) http://www.fwhc.org/health/moon.htm
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  • National Institute of Child Health & Human Development. "Menstrual Irregularities." May 24, 2007. (March 23, 2011)http://www.nichd.nih.gov/health/topics/Menstrual_Irregularities.cfm
  • National Institute of Child Health & Human Development. "Menstruation and the Menstrual Cycle." Sept. 10, 2006. (March 23, 2011)http://www.nichd.nih.gov/health/topics/menstruation_and_the_menstrual_cycle.cfm
  • National Institutes of Health. "Prior Stress Could Worsen Premenstrual Symptoms, NIH Study Finds." Aug. 23, 2010 (March 22, 2011)http://www.nichd.nih.gov/news/releases/082310-prior-stress-worsen-premenstrual-symptoms.cfm?from=women
  • U.S. Department of Health and Human Services, Office on Women's Health. "Menstruation and the Menstrual Cycle." Oct. 21, 2009 (March 22, 2011)http://www.womenshealth.gov/faq/menstruation.pdf
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