The Occasional Missed Period

Having a late or missed period can be a source of stress and anxiety, and is a common reason for visiting the gynecologist. Generally speaking, an isolated late or missed period is not a cause for concern. It is very common, even in women with cycles that are usually regular. There are many possible causes.

What Should I Do?

In women who are sexually active with male partners, it is important to take a home pregnancy test if your period is late. In most cases, a home pregnancy test found at your local drugstore is perfectly fine (there are low rates of both false positive and false negative results, but these are unusual). If a home pregnancy test is negative, and your period is more than a few days late, you can usually be reassured that you are not pregnant. If a home pregnancy test is positive, you should always make an appointment with your gynecologist.

Other Reasons for Missed Periods

If your pregnancy test is negative, there are many other possible reasons why your period might be late (or even skip an entire cycle). These are:

• Stress
• Change in body weight
• Increased exercise
• Poor sleep
• Travel across time zones
• Certain medications including birth control pills
• Aging

Stress

Stress can disrupt your menstrual cycle because of the way our bodies are designed to respond to stress, which is to shut down all non-essential bodily functions (like the reproductive system) at least temporarily. Your brain, which makes the first in a series of hormones that regulates your menstrual cycle, diverts this energy to “survival mode” in response to increased stress.

Increased Exercise and Changes in Weight

Frequent rigorous exercise (especially combined with low body fat) can be interpreted by your brain as “stress” and can disrupt your cycle in a similar way. On a related note, if you lose a lot of weight in a short amount of time, you are likely to notice some type of menstrual irregularity.

Being over or underweight can lead to changes in your menstrual by affecting how much estrogen your body produces. Both too much and too little estrogen can cause your cycle to be irregular or stop.

Medication

Taking certain medications can affect your menstrual cycle. For example, many medications work by affecting various hormones in your body including:

• Birth control pills
• Thyroid medication
• Steroids
• Antipsychotics  

Birth control pills prevent pregnancy in a few different ways including stopping ovulation, thickening cervical mucous (so sperm cannot enter the reproductive tract), and thinning the uterine lining (endometrium).

As this lining becomes thinner over the first few months on the pill, many women have irregular spotting or bleeding. Once the uterine lining is thinned out, many women notice that their period is much lighter/shorter and sometimes it stops coming altogether- there is simply nothing building up to shed each month. This is nothing to worry about and is, in fact, a benefit of being on the pill (and reverses once you stop it).

Sleep and Travel

Poor sleep, as well as frequent travel across time zones, can throw off your menstrual cycle by affecting your reproductive hormones as well as your melatonin levels, both of which can impact your ovulation and periods.

Age

Finally, as women enter perimenopause (the years leading up to menopause) they can start having late or missed periods as a result of the changes in their hormone levels during this phase.

If you have a late or missed period, don’t panic. In many cases, it’s the result of a temporary disruption and things will go back to normal. If they don’t, you should make an appointment with your gynecologist.

We can help figure out what might be going on, and discuss possible treatments with you. If irregular cycles become a pattern, especially if you frequently skip entire cycles or go 3 or more months without a period, you should be evaluated for underlying medical conditions and discuss treatment with your doctor.