Some people naturally have shorter menstrual cycles than others. However, very short cycles can sometimes indicate an underlying health condition, or another type of vaginal bleeding.
The menstrual cycle can vary from
Suddenly having shorter cycles than usual, very frequent bleeding, or other unexplained symptoms are signs that a person needs to speak with a doctor.
Read more to learn about the possible causes of a short cycle, when to contact a doctor, and more.
The menstrual cycle naturally varies in length. Although the average duration is 28 days, many people do not have a cycle that lasts this long.
Doctors consider a menstrual cycle of
When a person’s cycles are typically short, it is likely nothing to be worried about. However, if it is unusual or a person has other sudden changes in their period, there could be an underlying cause.
There are many causes of a short menstrual cycle, and for bleeding that a person may mistake for a period. They include:
Pregnancy
Some people have spotting during pregnancy, which they may mistake for a period. This does not necessarily suggest a problem during the early stages of pregnancy, as 15% to 25% of pregnant people bleed during the first trimester.
Spotting or light bleeding may occur 1 to 2 weeks after fertilization when the egg attaches to the uterine lining. This is called
Additionally, it is not uncommon to have light cervical bleeding during early pregnancy. Because more blood vessels are developing in this area, light spotting can occur.
Pregnancy loss
Although bleeding can be typical during pregnancy, it may sometimes indicate pregnancy loss. When bleeding is due to pregnancy loss, it may start as light spotting, but usually gets heavier.
A person experiencing a pregnancy loss may also have painful abdominal cramps and tissue discharge. Other symptoms of pregnancy loss may include:
- mild to severe back pain
- painful cramps or contractions
- white-pink mucus discharge
- clot-like discharge
In some cases, an ectopic pregnancy can cause bleeding. This is when the fertilized egg implants outside the uterus, usually in a fallopian tube. If the fallopian tube ruptures, it can cause bleeding and severe pain. People experiencing this should seek immediate medical attention.
Perimenopause
Perimenopause refers to the years leading up to menopause, which is when a menstruating person stops having periods. Perimenopause usually begins when a person is in their 30s or 40s.
During perimenopause, the ovaries produce varying amounts of the hormone estrogen, which causes menstrual cycle changes. This can make a person’s cycle longer or shorter and their flow lighter or heavier.
Other perimenopause symptoms may include:
Anovulatory cycle
An anovulatory cycle happens when a menstruating person’s ovaries do not release an egg. This can cause irregular and heavy bleeding. It is
When the ovaries do not release an egg, bleeding may occur due to changes in hormone levels. Symptoms of an anovulatory cycle include:
- irregular periods
- skipped periods
- lighter or heavier bleeding
- difficulty getting pregnant
Endometriosis
Endometriosis happens when endometrial tissue, which is similar to the uterine lining, grows outside the uterus. It is relatively common, affecting more than
The tissue usually grows in the pelvic area, often on the ovaries, fallopian tubes, and around the uterus. It may also grow in the vagina, bowels, bladder, rectum, and cervix.
During a person’s menstrual cycle, this endometrial tissue swells and bleeds like the uterine lining. This can cause severe menstrual cramps as well as bleeding between periods, which people may mistake for a shorter cycle.
Other symptoms include:
- heavy periods
- irregular periods
- pain during or after sex
- chronic low back or pelvic pain
- painful urination or bowel movements during menstruation
- bloating
- diarrhea
- nausea
Birth control
People who use hormonal birth control may experience breakthrough bleeding, which they may mistake for a period.
This can happen with the use of any type of birth control, but occurs more often with:
- the implant, which is a tiny rod that releases hormones
- low-dose and very low-dose birth control pills
- hormonal IUDs, small T-shaped devices placed in the cervix
A short menstrual cycle will not always affect fertility. Whether it does depends on the underlying cause.
If a person’s cycles are naturally short, they may have no difficulty conceiving. However, they may need to be mindful that the day they ovulate could be earlier than they expect.
A
Ovulation is when a person is most fertile, so this may affect when a person has sex if they are trying to conceive.
If a person has a shorter cycle for other reasons, such as anovulation, this may affect fertility.
Individuals should contact a doctor if they experience periods that occur less often than every
Other symptoms to discuss with a doctor include:
- periods that become irregular after being regular
- bleeding when they are not menstruating
- pelvic pain when they are not menstruating
- particularly heavy bleeding
- menstrual blood flow that contains blood clots larger than a quarter
- feeling dizzy or faint
- several missed periods
A short menstrual cycle is usually not a cause for concern if that is a person’s typical cycle time and they have no other symptoms.
However, if this is a change from their usual cycle or if they are having difficulty getting pregnant, they may have a condition that requires medical attention.
Many factors can cause a short menstrual cycle. Sometimes, people may mistake other types of vaginal bleeding for a period. Causes of this can include bleeding due to pregnancy, pregnancy loss, endometriosis, or breakthrough bleeding when using hormonal birth control.
If a person keeps having frequent bleeding, they should contact a doctor.