You and your roommate could always count on getting a visit from Aunt Flo at the same time each month. Like, to the point where you knew when to cue up the rom-coms on Netflix… and when to stay out of each others’ ways. But this month your period came a week before your roommate’s, annnd your household was edgy for two weeks straight.  

Getting your period a week early is a sign that your menstrual cycle is getting shorter, and a shorter cycle could be a sign that something else is going on with your body.   So, what does this mean? Read on and learn the different reasons your menstrual cycle could be changing. 

Short Vs. Normal Cycle

There’s no such thing as the perfect length for a menstrual cycle. The full menstrual cycle – which includes more than just your period – is different for everyone. One woman’s “normal” could be longer or shorter than yours. 

The average menstrual cycle is 21-35 days long. It begins on the first day of your period and lasts through ovulation and PMS. It starts over when you get your next period. Your period can last anywhere from two to seven days. [1] 

As you age and your body changes, your cycle can get longer or shorter. If your period’s off by a few days here and there, it’s typically not a cause for concern. But changes to your cycle could be your body’s way of telling you there’s an underlying problem. Here are some possible reasons your cycle is getting shorter.

Why Your Menstrual Cycle May Be Getting Shorter

If your periods are less than 21 days apart, that’s a sign of abnormal menstruation. Another sign of abnormal menstruation is having a period that’s much lighter than usual.[2]  Potential causes can include:  


If you love cardio, bless you – not everyone can run a treadmill with the speed cranked up to 6 mph for hours on end. You’re crushing it!

But if you’re seeing changes to your menstrual cycle, too much exercise may be to blame. Over-exercising can cause irregular menstrual cycles, or amenorrhea. This is when you lose your period altogether. [3]

Let a doctor know if you have menstrual cycle changes and exercise a lot. In the meantime, you can cut the speed down to 3.5 mph, because that’s still crushing it. 

Premature Ovarian Failure

Ovulation is the center of your menstrual cycle. It’s when the ovaries release an egg to be fertilized. When there’s a problem with ovulation, your period can change or go away.

Premature ovarian failure (POF) is also called premature menopause. This is when the ovaries stop doing their job before age 40. 

Menopause is the point in time when a woman’s menstrual period has stopped for a year. At this time, the ovaries stop releasing hormones for a regular monthly cycle. The average age for menopause is 51.[4] 

Premature menopause can occur when the ovarian follicles don’t function normally. The follicles may not turn into eggs to be released during ovulation. This causes missed or irregular periods. 

The symptoms of POF are: [4]

  • Irregular periods
  • Hot flashes or night sweats
  • Pain during sex
  • Vaginal dryness
  • Mood changes

If you’re under 40 and experiencing these symptoms, talk to your doctor. You may be experiencing premature menopause. The best way to treat menopausal symptoms is by getting to the root of the problem. The S’moo Menopause Collection is designed to correct menopausal hormone imbalances. Get relief today by trying the once-daily menopause supplements

Polycystic Ovary Syndrome (PCOS)

Irregular cycles aren’t always a sign of early menopause. It could be an indicator of polycystic ovary syndrome, or PCOS. 

In PCOS, hormone imbalances cause problems with ovulation. Many women with PCOS have anovulatory cycles, where the egg is not released. When this happens, you miss a period. Irregular menstrual cycles are a common symptom of PCOS. 

Women with PCOS have imbalanced sex hormones. High levels of androgens (male sex hormones) can prevent ovulation. [5]

One way to promote ovulation every month is to get your hormones balanced. Try a daily hormone balance supplements like S’moo Ovary Good. With seven vitamins, herbs, and minerals, one scoop a day is all you need for balanced hormones.*

High Stress Levels

A recent study showed acute stress can make women ovulate sooner. Hormones released during stress can cause an LH surge, which triggers ovulation. [6] This suggests early ovulation from stress can make your overall cycle shorter. 

So what is acute stress and how can you avoid it? Most of the time, stress is unavoidable – but the way you react to stress may keep you healthy. If you work in a high-stress environment (which, let’s be honest, is just about anywhere these days) find ways to cope with the chaos. 

Some mindfulness techniques and breathing exercises may help you get through everyday stressors. Keep a network of like-minded friends who’ll hear you out during hard times. Also, exercise is a good way to keep stress levels under control, but don’t overdo it!


Some medications can cause changes to your menstrual cycle or period. Always discuss your medications with your doctor. Bring up any concerns you have about medications and your cycle. 

Medications that can cause irregular periods include: [7] 

  • Antidepressants
  • Seizure medications
  • Thyroid medications
  • Blood thinners 
  • Nonsteroidal anti-inflammatory drugs (NSAIDs)
  • Chemotherapy 

There may be other medications that affect your hormones and cycle. Pay attention to your body any time you begin taking a new medication. 

Uterine Scarring

People with a history of multiple reproductive surgeries may develop uterine scarring.  In Asherman’s Syndrome, scar tissue develops in the uterus. The areas with scar tissue don’t bleed when you have a menstrual period. This can make your periods lighter than normal. Other risk factors for Asherman’s Syndrome are pelvic infections and cancer. [8] 


To prepare for breastfeeding, your body makes a hormone called prolactin. Both women and men produce prolactin. Too much prolactin in the bloodstream can disrupt ovulation. This can cause shorter cycles or missed periods. 

Non-pregnant women (and men) can have high prolactin. Breastfeeding women will have high levels of prolactin naturally. This is why breastfeeding women may have irregular periods. Hormones fluctuate a lot when you’re breastfeeding, which can also cause changes to your cycle. [9]

What Can You Do with a Short Menstrual Cycle?

How can you tell if your menstrual cycle is getting shorter? It’s a good idea to track your menstrual cycle to know what’s normal for you. Can’t remember what you had for breakfast yesterday, let alone the days you bled last month? Try a period tracking app to keep tabs on Aunt Flo.

If you notice your periods are starting to get closer together, it’s a sign your menstrual cycle is getting shorter. Pay attention to how many days you bleed and if your periods are heavier or lighter than normal. 

A changing menstrual cycle could be a sign of hormonal imbalances affecting ovulation. The S’moo is your one-stop shop for hormone balance support. Our products are backed by science and trusted by women with the most challenging hormone problems. Try S’moo Ovary Good, a hormone-balancing blend, to regulate your menstrual cycle today. 

*The content in this article is provided for informational purposes only. This is not intended to prevent, diagnose, treat, or cure any health conditions. It is not a substitute for professional medical advice or consultation. Talk to your doctor before making changes to your healthcare regimen. 


  1. Your changing body: Puberty in girls
  2. Abnormal menstruation
  3. Physical activity and your menstrual cycle
  4. Premature ovarian failure: Early menopause
  5. Polycystic ovaries
  6. Acute stress may induce ovulation in women
  7. Could My Meds Affect My Period?
  8. Asherman’s Syndrome
  9. Hyperprolactinemia (High Prolactin Levels)