Table of ContentsView AllTable of ContentsNormal Menstrual CycleCauses of a Shorter CycleWhen to Seek CareDiagnosis
Table of ContentsView All
View All
Table of Contents
Normal Menstrual Cycle
Causes of a Shorter Cycle
When to Seek Care
Diagnosis
A shorter menstrual cycle may result from natural aging, lifestyle factors, or health conditions. As people age, their cycles often shorten, with the follicular phase becoming shorter.Other factors like stress, medications, or changes in birth control methods can also influence cycle length.
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What Is a Normal Menstrual Cycle?
The average length of a menstrual cycle, defined as the number of days between periods, is 28 days on average across adults in all age groups. However, what’s considered normal varies between people and can vary between cycles as well.
Depending on when a personovulates, most cycles last 21 to 35 days. Bleeding times average three to seven days and often shorten as you age. A short period cycle is less than 21 days.
What Causes Your Menstrual Cycle to Get Shorter?
There are multiple factors that can contribute to a shorter time between periods or shorter bleeding times, including birth control, pregnancy, medications, lifestyle factors, and more. While many reasons are not a cause for concern, there is a possibility of a serious health condition such as anectopicpregnancy.
It’s important to monitor your cycle to alert your healthcare provider when necessary. This helps them to identify and treat any underlying health concerns early.
Age
Menstrual cycles naturally shorten with age, averaging 30 days for people under 19 and decreasing to around 28 days in the late 40s. This is largely due to changes in hormone levels, particularly a shorter follicular phase.
After age 50, cycles tend to lengthen again, averaging about 31 days, as the body transitions towardmenopause. Regularity also shifts over time, with cycles being less predictable during adolescence, stabilizing in the 30s, and becoming increasingly irregular after age 45.
These changes reflect lifetime fluctuations in reproductive hormones like estrogen and progesterone, which regulate ovulation and cycle timing.
Extreme Exercise
Typically, the menstrual cycle should return to normal if the intensity of exercise is reduced and the body regains hormonal balance. However, it may remain irregular or shorter as long as the intense exercise continues.
Weight Change
Sudden weight loss or being underweight can reduce estrogen levels, potentially leading to irregular or missed periods. On the other hand,obesityis linked to longer and more irregular cycles due to increases in estrogen levels; excess fat tissue produces additional estrogen, which may suppress normal ovarian function and interrupt the menstrual rhythm.
Birth Control
Some types of birth control can affect the length of your period or causeamenorrhea(absence of a period). This includes pills, rings, intrauterine devices (IUDs), or injections. When changes occur, they are usually within a few months after starting birth control. Changing the brand or type of birth control can also affect the length of your menstrual cycle.
Pregnancy
If someone is unaware of their pregnancy, they may mistakeimplantation bleedingfor a period. Implantation bleeding occurs when the embryo first burrows into the uterus, usually about 10 to 14 days after conception. It typically occurs around the same time as your period but is lighter than menstrual bleeding.
Breastfeeding
Ectopic Pregnancy
Anectopic pregnancyoccurs when a fertilized egg implants outside of the uterus. Unfortunately, a fetus cannot survive this type of pregnancy and it can cause severe health problems for a pregnant person. Ectopic pregnancies change how hormones behave, which in turn can affect periods.
Perimenopause
For people in their late 30s or 40s, a shorter period may indicateperimenopause—the time shortly before menopause. Hormones fluctuate during this time, causing people to skip their periods or experience irregular, heavier, or lighter cycles. The transition can last four to six years.
Stress
Stress causes the adrenal glands to release a hormone calledcortisol, which can disrupt the endocrine system. This affects how your body communicates with reproductive hormones such asestrogen, affecting your menstrual cycle.
Medications
Medications such as non-steroidal anti-inflammatory medications (NSAIDs), thyroid hormones, and steroids can shorten period bleeding time. The same is true if you’ve stopped taking some medications such as blood thinners.
While this is not an extensive list, other examples of medicines that may cause period changes include:
Transgenderpeople taking testosterone may experience lighter and shorter periods before they stop altogether. Keep in mind that hormone therapy doesn’t completely remove the risk of pregnancy.
Medical Conditions
Certain medical conditions can cause irregular bleeding, shorter cycles, or breakthrough bleeding. These include:
When to See a Healthcare Provider
Contact your healthcare provider if you experience the following:
Other changes in periods that indicate you should call your healthcare provider include:
Getting a Diagnosis
When necessary, the healthcare team may also suggest imaging tests such as:
Summary
A shorter menstrual cycle or bleeding period can be due to a number of causes, including pregnancy, birth control, health conditions, medications, stress, and more. You should contact a healthcare provider if your periods become irregular after being consistent or if they occur every 21 to 24 days or less. Additionally, seek medical advice if you experience other concerning symptoms like heavy bleeding, dizziness, or clots larger than a quarter.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
U.S. Department of Health and Human Services: Office on Women’s Health.Period problems.
Office on Women’s Health.Physical activity and your menstrual cycle.
U.S. Department of Health & Human Services: Office on Women’s Health.Birth control methods.
Hendriks E, MacNaughton H, MacKenzie MC.First Trimester Bleeding: Evaluation and Management.Am Fam Physician. 2019;99(3):166-174.
La Leche League International.Menstruation and breastfeeding.
Nemours Kids Health.Ectopic pregnancy (for parents).
The American College of Obstetricians and Gynecologists.My periods have changed. Is menopause around the corner?.
MedlinePlus.Tranexamic acid.
UpToDate.Patient education: heavy periods (beyond the basics).
University of California San Francisco.Information on testosterone hormone therapy.
Klein D, Paradise S, Reeder R.Amenorrhea: a systematic approach to diagnosis and management.Am Fam Physician. 2019;100(1):39-48. PMID:31259490.
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