A range of factors can cause a period to be early. If this happens every once in a while, it is likely no cause for concern, as variations in the menstrual cycle are common.

Early periods often result from hormonal changes, especially during puberty and perimenopause.

Many underlying medical conditions, including polycystic ovary syndrome (PCOS) and endometriosis, can also cause menstrual irregularities.

This article describes several possible causes of an early period, as well as their symptoms and treatments.

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Puberty refers to the time during which adolescents reach sexual maturity.

During puberty, the female body starts producing hormones — primarily estrogen and progesterone — that facilitate the physical changes often associated with the transition to maturity.

These changes include:

  • an increase in height and weight
  • increased fat storage in the buttocks, legs, and hips
  • enlarged breast tissue
  • increased hair growth on the arms, legs, armpits, and pubic area
  • skin changes, such as elevated oil production, blemishes, and acne

In addition to causing physical changes, the hormonal changes during puberty prepare the female body for reproduction.

The American College of Obstetricians and Gynecologists (ACOG) reports that, on average, females experience their first period between the ages of 12 and 13 years. The average menstrual cycle lasts for roughly 28 days, but some people have shorter or longer cycles.

Among adolescent females, the average cycle interval is 32.2 days, according to statistics from the ACOG. In the early years of menstruation, 90% of periods last 21–45 days, but it is possible to have cycles outside of this range. By the third year, 60–80% of menstrual cycles last 21–34 days.

For at least the first 6 years of having periods, a person’s periods may be irregular.

Treatment

Puberty is a natural process, and medical intervention is not usually necessary.

However, doctors may recommend hormonal therapy when females enter puberty very early or very late.

Diagnosis

If a doctor suspects that there is a problem related to the onset of puberty, they will review the adolescent’s medical history.

They may also perform a physical examination and run lab tests, including blood and imaging tests.

When to see a doctor

Parents and caregivers may wish to seek medical advice if a child has a menstrual period or develops other features of puberty before they reach 8 years of age.

This can indicate that a child is entering puberty sooner than they should, which doctors refer to as “precocious puberty.”

Meanwhile, female adolescents who do not show signs of breast development by the age of 13 years may have delayed puberty.

Delayed puberty can happen for numerous reasons, including insufficient body fat, genetics, and problems affecting the ovaries.

Treatments for issues concerning the onset of puberty vary, depending on the underlying cause.

Perimenopause, the transition to menopause, usually begins between the ages of 47 and 51 years.

It can cause fluctuations in levels of hormones, specifically estrogen and follicle stimulating hormone (FSH). Some people get their periods a few days early due to rising levels of FSH.

People can usually expect lighter and less frequent periods as levels of estrogen decrease throughout the transition.

Perimenopause can also cause:

  • longer or shorter periods
  • heavier or lighter bleeding
  • vaginal dryness
  • changes in libido
  • hot flashes
  • mood changes and irritability
  • difficulty sleeping

Treatment

Perimenopause refers to the time when the body naturally transitions into menopause. It is not a health problem that requires medical treatment.

However, perimenopause and menopause can cause mild-to-severe symptoms, and certain adjustments and medical interventions can help make the transition easier.

Below are some symptoms of the transition and tips for handling them:

  • Hot flashes: Keep the bedroom cool at night, drink plenty of water, and avoid potential triggers, including caffeine, alcohol, and spicy foods. Hormone therapy and some antidepressants may also help when hot flashes are severe.
  • Irregular periods: Low dose birth control pills can help stabilize erratic menstrual cycles.
  • Cramps and muscle pain: Over-the-counter pain relievers can help. Also, warm compresses can relax cramping muscles in the stomach and back.
  • Vaginal dryness: Lubricants and vaginal moisturizers can help alleviate symptoms.

Diagnosis

A doctor can tell whether a person is entering perimenopause by reviewing their medical history and possibly conducting a few routine tests.

They will ask about the date of the person’s last period and their symptoms.

To rule out medical issues that have symptoms similar to those of perimenopause, the doctor may order blood samples to evaluate the person’s hormone levels, thyroid function, and lipid profile.

When to see a doctor

It is advisable to see a doctor about any significant changes in menstrual cycles. Also, people currently going through perimenopause should tell a doctor if they experience:

  • heavy bleeding that soaks through a pad or tampon in under 2 hours
  • blood loss that exceeds 80 milliliters
  • new or worsening symptoms, particularly if any interfere with daily life
  • pain or bleeding during or after sex

Certain sexually transmitted infections (STIs), including chlamydia, gonorrhea, and syphilis, can cause vaginal bleeding or spotting between periods.

However, these bacterial infections do not always cause symptoms. If people do have symptoms, they usually include:

  • yellow discharge from the vagina or urethra
  • frequent urination
  • pain during sex or while urinating
  • rectal bleeding or discharge

STIs are very common. The Centers for Disease Control and Prevention (CDC) estimate that about 20% of people in the United States have an STI on any given day.

Treatment

Doctors treat these STIs with antibiotics. The right type and dosage will depend on the underlying condition requiring treatment.

Diagnosis

A person can undergo testing for common STIs at a doctor’s office or clinic.

Doctors use urine samples or vaginal swabs to test for gonorrhea and chlamydia, whereas testing for syphilis requires blood samples.

If a doctor suspects that the infection has spread to the central nervous system, they may also test the cerebrospinal fluid.

When to see a doctor

The ACOG recommends that women younger than 25 years and all others with a higher risk of infection undergo regular gonorrhea and chlamydia screening.

Risk factors for an STI include:

  • not using condoms consistently
  • having a current or previous STI
  • having multiple sexual partners
  • having a sexual partner who has multiple sexual partners
  • having sex with someone who has an STI

A person should see a doctor immediately if they notice any STI symptoms.

Light bleeding or spotting can occur when a fertilized egg attaches to the lining of the uterus. This usually occurs 1–2 weeks after conception and a few days earlier than an expected period.

Implantation bleeding appears much darker than a regular period because the blood stays in the body for longer.

Other signs of implantation bleeding can include:

  • abdominal cramps
  • nausea
  • bloating
  • sore or tender breasts
  • headaches
  • changes in body temperature

Implantation bleeding happens in 15–25% of pregnancies.

Treatment

As implantation bleeding is a normal sign of pregnancy and is not usually dangerous, there is no need for treatment.

Diagnosis

Implantation typically occurs about 6–10 days after ovulation and just before menstruation is due to begin.

People who notice light bleeding before they expect their period may wish to take a home pregnancy test once the bleeding stops.

When to see a doctor

People should report any unusual bleeding or spotting to a doctor and seek immediate medical attention if they experience:

  • excessively heavy or long lasting periods
  • severe menstrual cramps
  • pain in the abdomen, lower back, or pelvis
  • increased urination
  • pain during or after sex

Learn more about implantation bleeding and what to expect.

Medical professionals use the term miscarriage to refer to the loss of a pregnancy that occurs before 20 weeks.

Pregnancy loss can cause the following:

  • spotting or heavy vaginal bleeding
  • clot-like discharge from the vagina
  • pain in the abdomen or lower back

Experts say that up to 10% of confirmed pregnancies end in pregnancy loss but that this may actually occur in as many as 26% of all pregnancies. Pregnancy loss is more likely in the early stages, and some people may experience a loss before they know that they are pregnant.

Treatment

When pregnancy loss occurs, the body expels placental tissue through the vagina.

A doctor may perform a pelvic exam to check whether any of this tissue has remained inside the body.

If the individual does not naturally pass the tissue, the doctor may recommend medication or surgery.

Diagnosis

In addition to performing a pelvic exam, the doctor may check the person’s hormone levels and examine a sample of their vaginal discharge.

These tests can confirm that a pregnancy loss has occurred.

When to see a doctor

It is essential to see a doctor following any indications of pregnancy loss.

If pregnancy tissue remains in the uterus after such a loss, an infection can develop.

Signs to look for include:

  • persistent vaginal bleeding
  • severe cramps or other types of muscle pain
  • foul-smelling vaginal discharge

PCOS is a common condition that can affect 1 in 10 females of childbearing age.

Healthcare professionals do not yet know the cause, but a variety of factors, including imbalanced hormones and insulin resistance, could play a role.

PCOS may cause an early period, as irregular menstrual periods are a common symptom.

Other symptoms may include:

  • obesity
  • excess hair growth
  • acne and oily skin
  • fluid filled sacs in the ovaries

PCOS affects 5–10% of females aged 15–44 years.

Treatment

A person with PCOS can take medication to ease the symptoms and treat the condition.

A doctor may recommend taking birth control pills, which can help a person’s menstrual cycle become more regular, and anti-androgen medications, which block androgens — male sex hormones — and help reduce extra hair growth and acne.

Diagnosis

A doctor may diagnose PCOS by performing:

  • A pelvic exam: A doctor may look for an enlarged clitoris or enlarged, swollen ovaries.
  • A physical exam: This exam may involve taking a person’s blood pressure, checking their body mass index (BMI), and looking for signs of acne, hair thinning, or discolored skin.
  • Blood tests: A doctor may use a blood test to check a person’s hormone levels.
  • Sonogram: An ultrasound scan produces this image, which a doctor can check to see whether there are cysts on the ovaries.

When to see a doctor

Anyone experiencing irregular or early periods should see a doctor to rule out PCOS.

A person may be at higher risk of developing PCOS if someone in their family already has it or if they have obesity.

Endometriosis occurs when tissue similar to the lining of the endometrium grows outside of the uterus.

It can affect the menstrual cycle by causing:

  • heavy bleeding
  • spotting between periods
  • bleeding mid-cycle
  • irregular periods
  • irregular bleeding

Although the cause is unknown, hormones and genetics may play a role.

Endometriosis appears to be more common in females aged 30–40 years, but a person may be at a higher risk of developing the condition if:

  • they have not had children
  • a family member already has the condition
  • they experience menstrual cycles that last 27 days or less

About 11% of females in the U.S. live with endometriosis, according to the Office on Women’s Health.

Treatment

The treatment of endometriosis is likely to involve medications, which may include:

Surgery is also an option. According to a 2018 review, 95% of people who undergo surgery to remove lesions experience pain relief.

Diagnosis

A doctor can diagnose endometriosis by performing:

  • A pelvic exam: The doctor will look for cysts and scars behind the uterus.
  • An ultrasound: This imaging tests can help identify ovarian cysts.
  • Medication: A doctor may prescribe medication if an ultrasound has detected any cysts. Birth control pills can reduce the pain, and gonadotropin-releasing hormone agonists can lower the amount of estrogen the body produces. If pain improves, this can indicate that a person has endometriosis.
  • A laparoscopy: A doctor may perform this surgery to look at the endometrial-like tissue. They may also perform a biopsy.

When to see a doctor

A person should see a doctor if they are experiencing:

  • painful menstrual cramps
  • lower back pain
  • intestinal pain
  • spotting between periods
  • digestive problems

On its own, an early period does not tend to indicate a problem. However, if any other menstrual changes occur or a person has concerns, they should contact a doctor.

Hormonal fluctuations during puberty and perimenopause can cause periods to arrive sooner than expected.

Meanwhile, certain STIs, including chlamydia, gonorrhea, and syphilis, can cause vaginal bleeding between periods.

Also, implantation bleeding and pregnancy loss can sometimes resemble menstruation, as each can involve abdominal cramping and vaginal bleeding.

It is worth noting that implantation blood may be much darker than regular period blood. Anyone who is unsure may be able to confirm the cause of bleeding by taking a home pregnancy test.

During pregnancy loss, placental tissue exits the body as a red, clot-like discharge. Anyone who believes that they are experiencing this should contact a doctor immediately.