Instagram removed it (later saying it was an error.) Women shared it as an image of feminism. And likely everyone who saw it had at least an instant of surprise: such a sight, willingly displayed, is certainly uncommon. But menstruation should be all but uncommon: A rough calculation of how many women at any given time are menstruating results in over 300 million.

For centuries, menstruation has been associated with something dirty, disgraceful, embarrassing. Jyoti Sanghera, one of the members of the United Nations high commission on human rights, said at a 2013 UN event on women’s day: ”How can a normal, natural function be associated with shame, stigma, distaste, untouchability, taboo?”

The stigma is due, in part, to a lack of knowledge—so here is an attempt to shed light on how women around the world deal with their periods and how menstruation, and related businesses, are changing.

The basics

Menstruation is the shedding of the uterine lining which occurs, at the end of a woman’s cycle, in absence of a fertilized egg. Humans, primates, bats, and elephant shrews, are the female mammals who menstruate while other mammals, such as cats and dogs, follow a different cycle. A woman’s cycle usually lasts between 21 and 35 days (it can reach 45 in young teenagers) and menstruation usually lasts three to five days. Most women lose about 30 to 40 ml (1.3 oz) of blood (or, to be exact, menstrual fluid, which includes blood and mucosal tissue), although they can lose up to 80 ml.

The age of menarche (or the first menstruation) varies by country: in the US, girls get their first periods at 12 on average, but menarche can occur anywhere between eight and 15 years of age. Recent research suggests a link between the diet and age of menarche, positively correlating consumption of sugar-sweetened beverages with an earlier onset of menstruation in young women.

The improvement of living conditions through the 20th century has moved the average age of menarche three months earlier for every decade in industrialized countries, although studies suggest it has now stabilized or shows an upward tendency in several countries.

All the menstrual pains

Menstruation is seen as a challenge—and in many ways, it is. An estimated 50% to 60% women suffers from dysmenorrhea, or severe menstrual pain, which leads to the loss of 140 million working hours in the US alone, and is considered the leading cause of missed work days for young women. In some Asian countries (such as Japan and South Korea) women are granted paid “menstrual leave”—from two days a year to monthly leave.

The evolution of period management products

The sanitary protection market (or market for “feminine hygiene products,” a definition that belies the association of menstruation with something dirty) is massive—and has growth potential as women in developing countries start adopting menstruation management tools.

According to market research firm Euromonitor, as of 2015, the largest local market is in China ($11.9 billion), followed by Western Europe ($4.6 billion) the US ($3 billion), and Middle East and Africa ($1.7 billion).

By far, the preferred products are sanitary pads. Tampons, too, are widespread—though primarily in Western countries.

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Fasten your belt, spread your wings: The design of sanitary pads

Disposable sanitary pads are by far the most common and widely available menstrual management product. The design of pads has evolved significantly through the years, from reusable, homemade cloth napkins to disposable pads. Improvement in the design involved the addition of wings and adhesive in the late 1960s, which came to replace the belt needed to keep the pad in place, and the development of higher absorbing materials that would result in smaller, more comfortable pads with a lower risk of leakage.

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Some research suggests that the chemical bleach used to whiten most pads could be harmful. Further, disposing of used sanitary napkins is a problem in developing countries, especially in rural areas where waste disposal systems are inadequate. A woman would need about 16,800 pads in her life, and the materials they are made of make it difficult to burn or dispose of them without negatively impacting the environment.

Reusable pads are better in this respect, however they have another issues: Because of the savings they generate, they are often used in developing countries where women are sometimes unable to wash and sanitize them, or dry them properly (they are embarrassed to hang them outside.) This results in lack of hygiene: it is believed that in India, about 70% of female reproductive diseases are linked to poor menstrual hygiene.

Papyrus tampons date back to Egypt, 15th century BC

Tampons are increasingly commonplace in many parts of the world, yet the US is the only country where their sales are roughly comparable to those of sanitary pads. In many parts of the world, women are hesitant to insert tampons inside their body for fear of losing their virginity or because they find it uncomfortable.

In her 1981 book Everything You Must Know About Tampons, Nancy Friedman writes: ”The oldest printed medical document, papyrus ebers, refers to the use of soft papyrus tampons by Egyptian women in the fifteenth century BC. Roman women used wool tampons. Women in ancient Japan fashioned tampons out of paper, held them in place with a bandage, and changed them 10 to 12 times a day.” Tampons with applicators can be just as difficult as pads to dispose of, since they don’t biodegrade: According to Euromonitor, the Center for Marine Conservation claims that over 170,000 tampon applicators were collected along US coastal areas between 1998 and 1999.

Further, tampons—except when made of organic cotton—are, like pads, also bleached with potentially toxic substances, and lack of clinical trials fails to measure whether they have any long-term consequences for women’s health. One potential risk of tampon use is, however, well known: Toxic Shock Syndrome, a very rare, but potentially fatal bacterial infection, which is associated primarily with the use of tampons.

An alternative to tampons and pads

Much less common, though becoming increasingly popular especially in Western markets, are menstrual cups. Made of silicone, medical grade plastic or latex, menstrual cups are worn inside the vagina or at the cervix level and, rather than absorbing the fluid, they collect it. Once full, the cup can be removed, emptied, cleaned and reused. Concerns about the environment, the composition of tampons, and the expense generated by the purchase of disposable period management products made some women, primarily in the US, turn to menstrual cups.

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The first bell-shaped menstrual cup was patented in 1932. Other patents followed, until The Keeper, the first commercially successful cup was sold in 1987. While disposable in some cases, menstrual cups are generally reused—for up to several years—and cost about $30. They last up to 12 hours, versus a maximum of eight hours for tampons. The cups that sit at the cervix level such as Soft Cup can be worn during intercourse. However, the possibility of leakages, the need to sanitize the cup, and difficulties that women might encounter in its insertion, have made the majority of women reluctant to use them.

Product availability

According to this crowdsourced list of menstrual management products, disposable pads are available (at least in urban areas) in most countries, but they are harder to obtain in developing countries (especially in rural areas) and in areas under emergency conditions.

Marni Sommer, professor of socio-medical sciences at Columbia University, told Quartz that the lack of options for safely disposing of a pad is (alongside the lack of toilets) one of the reasons that girls don’t attend school during their periods. Sommer said that a lack of comprehensive studies makes it hard to quantify the impact of menstruation alone on school attendance. Often, she told Quartz, it’s a combination of factors that go together: Girls drop out of school because they have no access to supplies, but also because they attend what Sommer calls “girl-unfriendly schools,” or schools that, she explains:

  1. don’t have separate toilets for girls
  2. lack access to clean water
  3. don’t have access to proper sanitary product disposal
  4. don’t have separate environments for girls to wash and dry reusable cloths (especially an issue with boarding schools.)

Sommer shared this account of the issues by adolescent girls, aged 16 to 19, in a Ghanian boarding school:

We want sanitary pads. We want them to provide medicine. The school authorities should also advise the boys and let them know that this is a natural thing that girls go through and they should not be teasing us. It makes us very uncomfortable. They school should elect one teacher who is very friendly who we can go to so she can teach us about these things and how to manage them and all of that so that we will not be disgracing ourselves. They should provide us with water. Sometimes when this happens, and there is no water, you have to go and buy pure water and you see how it is small but sometimes, it is the only thing that you can do. You have blood all over you, what can you do? Sometimes also, even in the evening, when you want to bathe, because there is no water, you really can’t do anything. So you just go to the [empty class] room, change your pad, and then throw it away and wear a new one, and madam, you can’t help it. You just smell. But then that is not your fault. You need water.

Like lack of sanitation, limited access to pads leads to adoption of unhygienic solution (for instance, in certain communities cow-dung is used to absorb menstrual fluid) and to women risking violence if they are trying to clean themselves after dark.

The ultimate “pink tax”

The other thing about pads and tampons is that they can be relatively expensive. Agnieszka Wilson, executive director of NFCC International (formerly Nepal Female Care Center), told Quartz that the cost of sanitary supplies can become a burden and deter women in developing countries especially from purchasing them.

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In India, the annual expense for a supply of pads would be about Rs 2,240 ($36; calculated on market price for 20 pads per period). In a country where the average annual income is about $1,500 and an estimated 24.6% of the population lives on less than $1.25 a day, the purchase of sanitary products is particularly burdensome.

In Kenya, as Sabina Rubli reports:

the average cost of a package of sanitary pads is 75KSH—approximately $1 CAD [or $0.79] . While this may seem like a minimal amount of money, the average daily income for unskilled laborers is around $1.50 CAD, meaning that purchasing sanitary supplies each month is not financially possible for thousands of women.

Several initiatives are in place to provide poor women with pads (the preference would be for reusable pads, such as LunaPads) or even menstrual cups. But Susan Papp, director of policy and advocacy at nonprofit Women Deliver, told Quartz the best way to solve the issue is to encourage local production of supplies and “manufacturing within the market that [the producers] are serving.” Papp said external support may still be needed in areas where manufacturing is impractical because of the cost of materials or other factors.

There are cases, however, where the market for sanitary products could offer interesting entrepreneurial opportunities. This was the case for Arunachalam Muruganantham—nicknamed “Menstrual Man”—who, shocked by the lack of menstrual hygiene supplies in his family. Muruganantham developed low-cost alternatives—at about one-fortieth of the cost—to the pads available in the South Indian village where he lived. He had to face shame and ridicule, but was eventually victorious:

Blood isn’t blue—or, a long tradition of stigma

While the conditions of dealing with menstruation vary by country, one thing appears constant worldwide: the shame associated with it. The industry of feminine products has abundantly capitalized on that from offering ultra-white, bleached tampons and pads, to products with names such as Whisper, Carefree, Tampax Pearl (or Radiant). Packaging employs all the colors with the exception of anything close to actual red; there’s the ubiquitous blue liquid that replaces blood in commercials. Nothing about the feminine products marketing is geared towards feeling at ease around Aunt Flo.

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Once (and just once) Always, a pad company moved away from the blue liquid with an ad, designed by an intern at advertising agency Leo Burnett, that was saluted as innovative for portraying menstrual liquid as a (tiny, highly designed) red dot.

Marketers capitalize on period-specific products, from pink-packaged medications to tampon subscriptions that add treats to cater to the supposed sugar and chocolate cravings women have during their menses. Interestingly, menstruation isn’t included as one of the many body-monitoring functions of the Apple Watch, although there are some tracking apps

Even newer companies that reflect a more positive outlook toward menstruation—some offering monthly subscription to period management products and period underwear—occasionally talk about “the shame of the store.” Some advertisements have moved away from story lines about white-wearing, skydiving women who bleed blue from a beaker to promoting openness and offering less contrived visuals. The latest to follow this trend is period underwear brand Dear Kate, in which women remember the first time they got their period:

Certain cultures and religions express the stigma of menstruation much more strongly, promoting the idea that a menstruating woman is dirty.

The female members of the Dogon in Mali, the Huaulu of Indonesia, and certain communities of far west Nepal are sent to so-called “menstrual huts.” According to Wilson, the huts (which are called chhaupadi in Nepal) are about 35 by 50 feet wide and lack any sanitation. They are outside the village and women are forced to spend the entire duration of their period, which—aside from the obvious discomfort—puts them at risk for being assaulted. Menstrual huts are usually associated with tribal religions, and in Nepal, chhaupadi are connected to Hinduism.

Most of the world’s major religions stigmatize menstruation, more or less openly. Orthodox Jews are the strictest in this realm—a menstruating woman is niddah, impure, and the Jewish code of law forbids her from touching other people. In Islam, menstruation makes a woman unfit to attend religious ceremonies, and is considered dirty. Hinduism doesn’t directly speak of menstruation, but most Hindus forbid women from taking part to the regular domestic and religious life while menstruating. Further, some cultures believe women to be inauspicious during their periods, and so in India are not allowed to touch pickles (and, at times, people), or to sleep in the same room as their husband; in Italy, they are not supposed to make preserves (link in Italian).

Bet you didn’t know…

There is likely no such thing as premenstrual syndrome or PMS.

Cramps are real. Hormone-generated moodiness? Not so much. Something common enough to be described in detail by the US Department of Health pages might be no more than a myth. Psychologist Robyn Stein DeLuca reached this conclusions through research, which she discussed in a TED talk: “After five years of research, there is no consensus on the definition, the cause, the treatment, or even the existence of PMS.” Several studies conducted in New Zealand and Canada also have failed to link menses with mood swings.

Another? Women may not actually be able sync their periods with one another—there is a growing body of evidence suggesting that they don’t, and those observations have been purely coincidence. Even Martha McClintock, the author who in 1971 coined the definition of menstrual synchrony, agrees that it would be very rare.

And a connection to lunar phases? No link there either.

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