Whether you meticulously track your period or not, you probably still have a general sense of how long your menstrual cycle lasts — so it can be a bit alarming if it feels like your period comes around sooner or later than normal.
In this article, we’re covering everything you need to know about short periods and menstrual cycles, including why they happen, how they change as you age, and when you should seek guidance from your doctor.
Menstrual Cycle Length: What’s Normal and What’s a Shorter Menstrual Cycle?
What Guides Your Menstrual Cycle and Why Is My Cycle Getting Shorter?
The menstrual cycle is guided by four key reproductive hormones, including luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone.
These hormones work together to orchestrate key menstrual cycle phases and milestones, making sure to trigger ovulation at the end of the follicular phase and menstruation (i.e. your period) at the end of the luteal phase.
On average, a typical menstrual cycle lasts approximately 28 days. However, everyone’s cycle is unique and it’s perfectly normal if your menstrual cycle lasts as little as 21 days or as long as 35 days.
Even if you don’t keep track of your cycle in a diary or cycle-tracking app (like the Mira App), you still probably have a rough idea of how long your cycle lasts and what’s “normal” for you.
If you notice that your cycle is becoming shorter than normal, this could be a normal sign of aging (if you’re in your late 30s or older). It could also be caused by stress, weight gain, certain medications, or an underlying health concern.
Is a 21, 22, 23, or 24 Day Cycle Normal?
Yes. The standard health guidance is that “normal” menstrual cycles can last anywhere from 21 to 35 days. Although 21 days is still on the short end of the spectrum, it is still considered normal and not generally a cause for concern.
When Do Short Periods Fall Within a Short Menstrual Cycle?
A “short” menstrual cycle is a menstrual cycle that lasts fewer than 21 days. If your cycle is 21 days, your period would fall on the first day of your cycle, with your next period arriving sooner than 20 days later. The typical period can last anywhere from two to seven days, even if the cycle is short.
Common Causes of Short Menstrual Cycles
|
Common Causes of Short (<21 Days) Menstrual Cycles |
|
|
Cause |
Explanation |
|
Age |
Menstrual cycles become shorter and increasingly irregular in the run-up to menopause, with symptoms beginning as early as the mid-30s. |
|
Stress |
Stress hormones disrupt the hormones that regulate the menstrual cycle, which may cause menstrual cycles to become shorter. |
|
Weight Changes |
Sudden changes in weight can disrupt hormone levels, which may cause menstrual cycles to become shorter. |
|
Excessive Exercise |
Excessive exercise can cause the body to halt ovulation. This can cause menstrual cycles to become shorter. |
|
Medication |
Certain medications, such as hormonal birth control and NSAIDs can affect menstrual cycle timing. |
|
Underlying Medical Conditions |
Certain underlying medical conditions, such as polycystic ovary syndrome (PCOS) and thyroid disorders can disrupt menstrual cycle timing. |
|
Pregnancy or Breastfeeding |
It’s common to experience irregular cycles following pregnancy and/or breastfeeding. |
Why Your Menstrual Cycle Gets Shorter With Age
It is natural for your period to vary in duration and volume over the course of your life. For example, periods can be more irregular during puberty as hormone levels adjust ahead of adulthood. It’s also normal for periods to become lighter and more irregular later in life ahead of menopause.
Can Stress Cause a Sudden Change in Menstrual Cycle Length?
Yes. Stress can disrupt hormone levels, which can impact the menstrual cycle. When the body is stressed, it ramps up the production of a hormone called cortisol. This increase in cortisol levels can cause your period to be lighter than normal and/or delayed. It can also cause you to skip a period.
How Weight Changes Affect Short Period Cycles
Losing or gaining a significant amount of weight in a short period of time can also disrupt your hormone levels. This disruption can of course lead to lighter periods, missed periods, and irregular periods.
Can Excessive Exercise Lead to Shorter Menstrual Cycle Symptoms?
Individuals who exercise excessively may burn more calories than they consume. When this occurs for a prolonged period of time, it can cause the body to halt certain non-critical functions (such as ovulation) in order to prioritize more critical functions (such as breathing). This can lead to lighter and missed periods.
Medications That Trigger Shorter Period Cycles
Certain medications are also known to impact your period. This includes hormonal birth control, which causes “breakthrough bleeding” and is typically much lighter than a normal period (although individual experiences can vary greatly).
Other medications that may affect your period include certain blood clot medications, aspirin and NSAIDs, thyroid medication, antidepressants, epilepsy medication, and chemotherapy.
Underlying Medical Conditions and Shorter Menstrual Cycle
Certain medical conditions can also disrupt your body’s ability to balance its hormones and/or have a regular cycle. Potential underlying conditions that may affect your cycle include polycystic ovarian syndrome (PCOS), ovarian cysts, thyroid disorders, premature ovarian failure, cervical stenosis, uterine fibroids, and uterine polyps.
Shorter Cycles After Pregnancy or Miscarriage
If you have recently been pregnant or experienced a miscarriage, it can take several cycles for your hormones to readjust back to their normal levels. As your body recovers, it’s common to experience light and irregular periods.
Why Is My Menstrual Cycle Getting Shorter in My 30s and 40s?
Why Is My Menstrual Cycle Getting Shorter in My Late 30s?
During your early 30s, your menstrual cycle will most likely be similar to how it was in your 20s. By now, you may also be more aware of what’s “normal” for you — which is extremely helpful for spotting any new changes or trends.
Once you reach your mid to late 30s, you may notice that your period is a bit of a mixed bag. This is especially true if you have recently had children.
On average, the menstrual cycle does tend to become shorter as you get older, as the follicular phase shortens with age. This is supported by research that suggests median cycle length decreases by approximately one day in women over the age of 40 compared to those between the ages of 18 and 24.
If you start to notice that your cycle is shorter and less frequent than normal, this could be a sign of perimenopause.
Why Is My Menstrual Cycle Getting Shorter in My 40s?
By the time you reach your 40s, your menstrual cycle is likely to become increasingly irregular and shorter. It may also be lighter than it was in your 30s.
Again, this is due to decreasing estrogen and progesterone levels as you approach menopause.
Other common symptoms of menopause include mood swings, hot flashes, night sweats, vaginal dryness, insomnia, and low libido.
If you have gone 12 months in a row without your period, this means that you have officially reached menopause.
A Little Extra Support From an Expert Can Go a Long Way
If you haven’t spoken with your doctor about your changing period patterns ahead of menopause, it’s a good idea to schedule a check-up so they can help you prepare for this next phase of life.
For further insights into what’s going on inside your body, you can also start tracking your hormones at home with the help of Mira’s Menopause Transitions Kit. With regular hormone tracking, you can define your menopause stage, navigate your symptoms, and pinpoint significant changes to your menstrual cycle before you officially reach menopause.
If you are struggling to navigate the physical and emotional symptoms of menopause on your own, it may also be worth speaking with a hormone health specialist. For example, the specialists in our Hormone Health Clinic can help you understand your hormone charts and provide practical advice for symptom management.
When to Worry About Short Periods or Sudden Cycle Changes
Your menstrual cycle will not always be perfect, and it’s completely normal for its patterns to vary over the course of your life depending on your age, lifestyle, medications, and health.
However, there are certain situations where you should seek professional medical guidance as soon as possible.
The following table highlights common scenarios where you should speak to your doctor.
|
When to Speak With Your Doctor About Your Menstrual Cycle Length |
|||
|
Cycle Length/Frequency and Associated Symptoms |
Age |
Speak to Doctor? |
Potential Underlying Causes and Explanation |
|
Sudden irregular period |
Under 45 |
Yes |
Stress, weight changes, excessive exercise, PCOS, thyroid dysfunction, medication changes |
|
Sudden irregular period |
Over 45 |
Yes |
Perimenopause, thyroid dysfunction, uterine fibroids, medication changes |
|
Cycle typically lasts between 21 to 35 days |
Any age |
No |
This is a normal, healthy range for a menstrual cycle |
|
Cycle is typically shorter than 21 days or longer than 35 days |
Under 45 |
Yes |
Stress, weight changes, excessive exercise, PCOS, thyroid dysfunction, medication changes |
|
Cycle is typically shorter than 21 days or longer than 35 days |
Over 45 |
Yes |
Perimenopause, thyroid dysfunction, uterine fibroids, medication changes |
|
Period/menstruation typically lasts longer than 7 days |
Any age |
Yes |
Hormone imbalance, PCOS, uterine fibroids or polyps, thyroid dysfunction |
|
Period is accompanied by debilitating cramps, pain, and/or emotional turmoil that interrupts your daily life and routine. |
Any age |
Yes |
Endometriosis, Premenstrual Dysphoric Disorder (PMDD), pelvic inflammatory disease (PID) |
You should also speak with your doctor if you are under the age of 35 and have been trying to get pregnant for more than one year, or if you’re over the age of 35 and have been trying to get pregnant for more than six months.
Final Thoughts on Shorter Menstrual Cycles
Everyone’s menstrual cycle is different. And the more you know about your own cycle, the better you’ll be able to determine what is “normal” for you.
One of the best ways to stay in tune with your body and cycle is by tracking your hormones and cycle symptoms. For more information on menstrual cycles, hormones, and menopause, you may find our library of blogs, eBooks, and webinars helpful.
Frequently Asked Questions
Why are my periods getting shorter?
Your periods may be getting shorter for a number of reasons, such as age, proximity to menopause, underlying health conditions, stress, or weight gain.
If you start to notice that your periods are becoming increasingly shorter, it’s a good idea to start tracking your cycle dates and symptoms in a diary or cycle-tracking app. You should then bring up any concerns at your next checkup with your doctor.
Is it normal to have a 22 day cycle or 23 day cycle?
Yes. It is considered normal for a menstrual cycle to last between 21 and 35 days.
Do 21 day menstrual cycles cause infertility?
No. 21 day menstrual cycles are considered normal and should not have a negative impact on fertility.
