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A menstrual period is vaginal bleeding that occurs at the end of the menstrual cycle. Each month, the body prepares itself for a possible pregnancy. The uterus develops a thicker lining, and the ovaries release an egg that can be fertilized by sperm.

If the egg isn’t fertilized, pregnancy won’t occur during that cycle. The body then sheds the built-up uterine lining. The result is a period, or menstruation.

Most people with a uterus will have their first period between ages 11 and 14. Periods will continue regularly (usually monthly) until menopause, or about age 51.

Learn more about the facts and statistics of menstruation below.

The average menstrual cycle is 24 to 38 days. The typical period lasts 4 to 8 days.

Monthly, or regular, periods are a sign your cycle is normal. Your body is working to prepare for a possible pregnancy.

In addition to bleeding, 90 percent of people who menstruate say they experience various symptoms. Food cravings are one common symptom. In fact, a 2017 study found that almost half of American women crave chocolate at the start of their period.

Breast tenderness is another common period symptom. It can peak in the days just before menstruation starts. A surge in the hormones estrogen and progesterone leads to enlarged breast ducts and swollen milk glands. The result is soreness and swelling.

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Meanwhile, period pain (also called dysmenorrhea) is another common symptom. More than half of menstruating people experience some pain around their period.

Prostaglandins are the cause of this pain. These are chemicals that trigger muscle contractions in your uterus. These hormones help the body shed the excess uterine lining, which can cause pain and cramping in the first days of your period.

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Some people don’t have regular periods. Intense exercise or certain medical conditions can lead to irregular periods. Irregular periods can also occur in people who are:

Moreover, a 2012 study found 32 to 40 percent of people who have periods report their pain is so severe that they have to miss work or school.

The most common period-related health conditions include the following.


Endometriosis causes tissue that’s similar to the lining of the uterus to grow in other parts of your body. This can lead to:

  • severe pain
  • cramping
  • heavy periods

Endometriosis affects 1 in 10 women between the ages of 15 and 49, estimates the American College of Obstetricians and Gynecologists (ACOG). The ACOG notes that 30 to 50 percent of people with the disorder will experience infertility.

Uterine fibroid

These noncancerous tumors develop between the layers of tissue in your uterus. Many people with a uterus will develop at least one fibroid during their lifetime.


Menorrhagia is very heavy menstrual bleeding. Typical periods produce 2 to 3 tablespoons of menstrual blood. People with menorrhagia can produce more than twice that amount.

More than 10 million American women have this condition, estimates the Centers for Disease Control and Prevention.


Premenstrual syndrome (PMS) is a series of symptoms that typically occur 1 to 2 weeks before the start of a period. Symptoms can include:

  • headache
  • fatigue
  • bloating
  • irritability

PMS affects as many as 3 in 4 women, according to


Premenstrual dysphoric disorder (PMDD) is similar to PMS, but it’s more severe.

It can cause:

  • depression
  • tension
  • severe mood shifts
  • lasting anger or irritability

Experts estimate about 5 percent of women experience PMDD.

Poor menstrual hygiene

Poor menstrual hygiene is also a health concern during your period. Blood and tissue loss during a period can lead to bacterial issues.

This can pose a serious health issue if menstrual products aren’t available or basic sanitation utilities aren’t accessible, such as clean water.

Each year in the United States, people spend upward of $2 billion on menstrual products. In their lifetime, the average menstruating person uses almost 17,000 tampons or pads.

This is both a personal cost to the individual and an environmental cost to the planet. Many of these products don’t easily degrade in landfills.

However, more than 16.9 million American women live in poverty and may not have access to menstrual products and medications that treat symptoms. There are also reports suggesting people in jail or prison often don’t have access to tampons or pads. These necessary products may be used as bargaining chips and traded for food or favor.

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In the United States, sales tax is frequently imposed on menstrual products. Currently, five states don’t charge sales tax:

  • Alaska
  • Delaware
  • Montana
  • New Hampshire
  • Oregon

21 states have specifically exempted these products from the so-called “tampon tax”:

  • California
  • Connecticut
  • Florida
  • Iowa
  • Illinois
  • Louisiana
  • Maine
  • Maryland
  • Massachusetts
  • Michigan
  • Minnesota
  • Nebraska
  • Nevada
  • New Jersey
  • New Mexico
  • New York
  • Ohio
  • Pennsylvania
  • Rhode Island
  • Vermont
  • Washington

Lawmakers from other states have introduced measures to remove the taxes on these products.

Access to menstrual products can be complicated elsewhere, as well. In Kenya, for example, half of all school-age women don’t have access to menstrual pads. Many also don’t have access to toilets and clean water. That frequently leads to missed school days, and some drop out of school entirely.

The stigma surrounding menstruation dates back centuries. References to menstruation are found in the Bible, Quran, and Pliny the Elder’s “Natural History.”

In these references, menstruation is referred to as “harm” and “unclean,” and something that can turn “new wine sour.”

Decades of faulty research did little to dispel the stigma that surrounds periods, too.

In 1920, Dr. Béla Schick coined the phrase “menotoxin” for a theory he had that women produce toxins during menstruation.

Schick reached this conclusion after a nurse who was menstruating handled a bouquet of flowers. Schick observed that those specific flowers wilted sooner than flowers the nurse didn’t touch. He decided her period was the cause.

In the 1950s, researchers injected menstrual blood in animals to test the toxic theory. The blood did, in fact, kill the animals. But it was proven years later that the death was a result of bacterial contamination in the blood, not a toxic effect.

By 1974, researchers had identified that menstruation taboos may be closely tied to how men participate in procreative activities. In other words, the less men are involved with childbirth and childrearing, the more distasteful a period is to them.

Period hygiene has also been an ever-evolving production.

In 1897, Lister’s Towels were introduced by Johnson & Johnson as the first mass-produced and disposable menstrual pad. These were far from the period pads of today. They were thick pads of material worn inside undergarments.

The Hoosier Ladies’ Sanitary Belt came a few decades after the turn of the century. The belt was a series of straps meant to hold reusable sanitary pads in place.

A few short years later, in 1929, Dr. Earle Haas invented the first tampon. His idea came from a friend who mentioned using a sea sponge tucked into her vagina as a way to absorb period blood.

The adhesive sticky pads used today weren’t introduced until the 1980s. Since then, they’ve been honed and updated to meet changing lifestyle, flow, and shape needs.

Today’s period products seek to solve many of the issues menstruating individuals have dealt with for decades, from leaks and period tracking to cost. They’re also helping remove the stigma that often surrounds menstruation. Plus, they seek to solve environmental and financial concerns.

These products include reusable menstrual cups and period underwear. There are also many smartphone apps that can help people better understand how their body prepares for, and acts during, their period.

Much has been done to remove the stigma of menstruation and to help people care for themselves during their period, but there’s still work to do.

In Britain, a 2017 survey from Plan International reported that 1 in 7 girls say they’ve struggled to afford menstrual protection. More than 1 in 10 girls have had to improvise menstrual wear because they couldn’t afford proper products.

Though the United Kingdom was set to drop taxes on tampons and other menstrual products, Brexit talks had stalled the final removal of the levy. The tampon tax was finally eliminated in 2021 in the UK.

In Nepal, a 21-year-old woman died from smoke inhalation after she lit a fire to keep warm during “chhaupadi.”

In this Nepalese practice, menstruating Hindu girls and women are forced from their home to sleep outside in huts or cattle sheds until their period ends. Temperatures can fall into the single digits or lower during winter, but the huts may not be heated or insulated enough to provide adequate warmth.

In parts of India, some women are forced to isolate themselves in much the same way.

Not every culture shuns menstruating individuals because of this natural cycle, though.

In some places in Africa, the onset of menstruation is viewed as a passage from one phase of life to the next. It’s a vaulted and valued experience. Specific huts or homes are set aside for women to stay in when they have their first period. They’re joined by their female family members and other women during this time.

Meanwhile, countries like Canada, which dropped taxes on tampons and other menstrual products in 2015, are looking to ease the financial concerns of getting a period.

In 2018, the United Nations (UN) reported that the shame, stigma, and misinformation that surround periods can lead to serious health and human rights concerns. That’s why they declared menstrual hygiene an issue that affects public health, gender equality, and human rights.

It’s also why the UN has added it to the 2030 Agenda. This is a 15-year plan for sustainable social and economic development that creators believe can help end poverty, hunger, and lack of access to healthcare.