Despite their lack of first-hand experience, men dominated gynaecology for centuries, which probably partly accounts for some of the absurd theories swirling around menstruation. The Ancient Roman writer Pliny the Elder warned that menstruating people could turn seeds sterile and make fruits fall from the trees. A look from a menstruating person would dim a mirror’s brightness. A glance could kill a swarm of bees. Such myths persisted for millennia. A 1956 account reported that Suffolk butchers wouldn’t let females near ham: if a menstruating person touched the hams, the meat would turn bad. Similarly, in 1982, a Leicestershire woman recounted that menstruating people should not milk cows or make butter.1
Dismissing such stories as rural folklore would be easy – if doctors did not recently believe equally absurd theories. In 1920, the Hungarian-born American paediatrician Dr Béla Schick claimed that if a person on the first to third day of menstruation held freshly cut flowers for 10-30 minutes the plants would wither in a few hours.2 A couple of years later, researchers claimed that menstrual blood, serum and ‘practically all the body secretions of menstruating’ people contained a substance that was toxic to plants and animals.2
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In Period: The Real Story of Menstruation (Princeton University Press), Kate Clancy, Professor of Anthropology at the University of Illinois Urbana-Champaign, notes that as late as the 1970s some researchers believed that menstruating people released a ‘menotoxin’. ‘Testing underlying assumptions can be powerful,’ she told IN. ‘When you test the underlying assumption of the menotoxin and its historical context it becomes clear how much of that scientific idea and biological theories more widely are cultural constructions.’
However, before today’s professionals grow too complacent: Professor Clancy cites an on-line survey of 518 US paediatricians. Only 48.9% and 40.2% of female and male paediatricians knew the maximum time for which tampons can be safely left inserted (8 hours). Only 85.4% and 66.0% of female and male paediatricians knew that women and girls can swim in the ocean with a tampon inserted. Just 66.8% and 44.3% respectively knew that women and girls can sleep with a tampon inserted, provided they replace the tampon within 8 hours.3
Period is more than a popular science book. It’s a polemic against the male-dominated view of gynaecology. Often Period takes an overlooked perspective, such as that people from different genders menstruate, and forces you to rethink your assumptions, not just about menses but also regarding autoimmune disease, preeclampsia and even the advice you offer about fertility.
Unlearning disgust and bias
For instance, the widespread disgust around menstruation seems deeply ingrained. Period cites a investigation about menstrual stigma involving a paid actor who pretended to be part of a study on productivity. As the actor fumbled in her bag for a lip balm, she dropped either a hair clip or an unused tampon. Study participants who saw the actor drop a tampon liked her less, felt she was less competent and chose to sit further away than those who were present when she dropped the clip.
Disgust evolved to protect against infection.4 So, we innately experience disgust to faeces, vomit and rotten food. Learning builds on this innate foundation. For example, cultural beliefs, laws and behaviours (manners) about purity and pollution reduce contagion and we copy other people in our culture (social learning).4 ‘My guess is that people would not have the same reaction to an unused bandage being dropped as to a tampon, which is what makes this more about specific disgust reactions to menstruation. But it certainly would be interesting to test!,’ says Professor Clancy. ‘I’d be very curious how many disgust reactions are truly automatic rather than learned.’
Professor Clancy suggests that nurses should initiate conversations regarding menstrual cycles, menstruation and other aspects of intimate health. ‘Signage about menstruation, leaflets and so on can lower the barriers to initiating conversations,’ Professor Clancy says. ‘Make sure you explain about low-cost menstrual products. I hope my book empowers nurses, people who have periods and the public more widely to address the stigma that still surrounds menstruation.’
Science is supposed to be objective. But that’s particularly difficult in biological or medical research. Physicists often use theoretical frameworks to guide experiments. So, physicists predicted some subatomic particles decades before they were discovered.5 Biologists have fewer theoretical frameworks, which can result in unconscious bias and experiments that confirm, rather than test, hypotheses.6 ‘We need to raise awareness of our biases,’ Professor Clancy says. ‘Trying to erase biases is often foolish. All you do is send them underground, but they don’t go away. Awareness of one’s perspective, lived experiences and potential biases is far more useful than trying to avoid bias.’
Until recently, for instance, male-dominated science’s a priori assumptions (something regarded as true without any evidence or proof) meant that menstrual disorders languished in the intellectual doldrums. ‘Every menstrual disorder is embarrassingly understudied and treatments are few and far between,’ Professor Clancy notes. ‘We have overfocused on how fertility relates to menstrual disorders while under-focusing on pain and quality of life. We require incredibly invasive testing, such as salpingograms, biopsies and laparoscopic surgery, because so little effort has gone into, for example, understanding how menstrual effluent could help us develop appropriate biomarkers to assess risk and diagnose disease.’
Professor Clancy’s background is in anthropology. She explains that anthropologists pay attention to lived experiences and withhold judgement until they have listened to and explored areas of agreement and discordance. ‘We try to avoid a priori assumptions by exploring more grounded approaches that involve a lot more interaction with participants and their experiences,’ says Professor Clancy. ‘At its core, feminist science tests assumptions, makes sure our work is grounded in history and puts attention on how power works.
COVID-19 and menstruation
In 2021, for example, Professor Clancy experienced an early and very heavy period after her SARS-CoV-2 vaccination. So, she tweeted asking whether other people had experienced menstrual changes after receiving the vaccine. Professor Clancy and several colleagues then put together a survey, which received 22,000 responses in the first week and more than 80,000 in the first month. Many reported that families, doctors and other health professionals were ‘dismissive and rude’ about menstrual changes associated with the vaccine.
‘Every paper shows that at least some participants experience menstrual changes. The findings are only getting more robust, especially since most of these studies are prospective,’ says Professor Clancy. ‘We resisted the temptation to not inquire after vaccine adverse effects because to do so was somehow ‘anti-vax’. By listening to participants, asking about the historical context of clinical trials and exploring clinical trials’ most basic assumptions about what symptoms were worth paying attention to, we built a powerful case that menstrual changes exist. Doing this improved transparency and made patients feel seen. We suspect that our inquires increased rather than decreased trust and offered an opportunity to help people distinguish between menstrual changes that are environmental responses and those that signal harm to fertility.’
Professor Clancy makes a wider point. ‘The fact that so many doctors were surprised that an immunogenic vaccine could induce a downstream haemostatic response in an organ that bleeds and clots blew my mind. It makes me wonder how much they are taught about the menstrual cycle or the uterus. The most obvious practical outcome is that we start to analyse the menstrual cycle in more of our work, including how immune function and dysfunction affects and is affected by the menstrual cycle.’
The X factor
‘Anecdotally, people with chronic autoimmune diseases may report experiencing flares around menses – this would match with our lab’s finding that a rise in C-reactive protein [a marker of inflammation] is common at this time in the cycle,’ Professor Clancy says. ‘But we’re missing much about how the reproductive-immune axis connects to the lived experiences of people with autoimmune diseases.’
About three-quarters of people who have autoimmune diseases are females.7 The X chromosome contains several important immune genes and strongly influences immunity. So, to equalise the genetic dose, one X chromosome in females is inactivated. The inactivation isn’t perfect. This means that XX females can end up having two copies of genes in a way that an XY male cannot. Overexpression of immune genes on the X chromosome can lead to more robust responses in females, which may contribute to the increased autoimmune risk.7
Furthermore, the immune system produces several types of lymphocyte. One subtype of ‘helper’ T cells type 1 (Th1) protects against intracellular bacterial and viral infections, and cancer cells. Th2 cells attack parasitic worms. Th17 lymphocytes attack extracellular bacteria. Abnormal Th1 and Th17 responses contribute to autoimmune diseases. Aberrant Th2 responses drive allergic asthma, atopic dermatitis and other allergies.8,9 The responses overlap, but Professor Clancy notes that men generally have stronger Th1 responses than women, which contributes to the sex-difference in autoimmune disease.
Hormones also influence autoimmunity.10 Of course, steroids are potent treatments for autoimmune diseases, some, but not all, of which improve during pregnancy.7,11 Professor Clancy suggests that rather than gender, research should focus on the dominant sex hormones. She suggests that a testosterone-dominant person may show different autoimmune responses to someone who is oestrogen dominant.
‘Autoimmune disease may also be related to transposons – there’s a lot going on!’ says Professor Clancy. Biologists often call transposons ‘jumping genes’: DNA sequences that can insert at several places in the genome either by switching position or inserting copies. The female scientist who discovered transposons, overturned entrenched biological dogma that genes were stable areas of chromosomes: like pearls on a string.12
Sweetcorn, a type of maize, is not, necessarily, a uniform yellow. The kernels can be a kaleidoscope of colour – red, blue, white, brown and black – sometimes on the same stalk. During the 1940s, the US geneticist Barbara McClintock realised that a break in the chromosome influenced colour. This break could change position. The reaction among the scientific establishment was, McClintock recalled, ‘puzzlement, even hostility... they didn’t understand it; didn’t take it seriously’. Time proved McClintock right and she was the sole winner of the 1983 Nobel Prize in Physiology or Medicine.12
Counselling about preeclampsia
Nurses can use the insights in Period to help counsel patients about preeclampsia. A UK study reviewed 1,899,150 pregnancies among 1,303,365 women. Of the pregnancies, 2.42% were preeclamptic. Preeclampsia usually developed during the first (76.64% of cases) and/or second (17.43%) pregnancy.13
‘Preeclampsia occurs due to incomplete placentation. In other words, the syncytiotrophoblast [a continuous cell layer in direct contact with the mother’s blood] does not invade the uterine wall quite as deeply as in a healthy pregnancy. Preeclampsia may have multiple origins. My interest in preeclampsia relates to situations where the person hasn’t menstruated that many times – someone who is very young or it’s their first pregnancy. Their uterus has not had much practice at building the tissue architecture to support pregnancy. There are also factors on the trophoblast [the outer layer of a blastocyst, the early embryo, that develops into much of the placenta] side that are important to think about,’ Professor Clancy says.
‘Preeclampsia is often silent. Many people have no symptoms other than elevated blood pressure. So, it’s important to take that marker seriously,’ Professor Clancy says. ‘The COVID-19 pandemic made pregnancy far more dangerous. COVID-19 increases the risk of preeclampsia – possibly especially for postpartum preeclampsia. Given the state of maternal health care, many postpartum people do not get enough visits postpartum to catch preeclampsia, which is very scary.’
Professor Clancy suggests that midwives and nurses should work with their professional societies to lobby for more home visits and better postpartum care. ‘I’d wear a mask and encouraging everyone else to do so as well,’ she says. ‘This is a very dangerous time to be pregnant and it saddens me that we have left pregnant people so completely out of the conversation around COVID even though it’s teratogenic.’
Counselling about fertility preservation
Follicular waves exemplify biology’s intricate choreography. ‘Follicular waves are so cool!’ Professor Clancy exclaims. Antral follicles (also called Graafian follicles), surround and protect the developing oocyte, and grow in patterns known as follicular waves.14 During the initial phase, a group of follicles grows at similar rates. During major waves, a follicle becomes dominant after about two days, continues to grow and is ovulated. The other follicles undergo degeneration and resorption, a process called atresia. During minor waves, all follicles undergo atresia. Each cycle includes 2 or 3 follicular waves as combinations of minor and major: in one study, 75% of women experienced 2 waves, usually a minor followed by major wave.14
‘The findings have important implications for fertility preservation,’ Professor Clancy says. ‘Ovulation stimulation protocols can be done at any time during the cycle, which is exciting for people who are undergoing cancer treatments or who are older and have limited chances. Follicular waves also mean that we should be a bit more cautious about the placebo week of typical hormonal contraception. Follicles are still active during the placebo phase. To me, what’s exciting is more the broader implications around how we conceptualise reproduction. The ovaries are incredibly active and agentic, which significantly disrupts our usual narrative.’
As gynaecology languished in the intellectual doldrums for so long, Period is filled with unanswered questions. ‘There is much we still don’t know about the specifics of the human uterus and trophoblast because our reproduction is so unique,’ Professor Clancy says. Some labs use mouse models because, like humans, mice have haemochorial placentation (the foetus’ outermost epithelium bathes in maternal blood). But mouse syncytins (proteins that facilitate cell–cell fusion) are completely different from ours and their placentation is far less invasive. ‘Some scientists use a sheep model for polycystic ovary syndrome, but again their uterus is quite different from ours,’ she adds.
‘Ethical limitations make it hard to understand, for instance, why so many pregnancies end early. We understand the big picture of why chromosomal abnormalities drive many miscarriages. But it seems that we do not have the full mechanistic picture,’ Professor Clancy comments.
‘We also push solutions that suppress menstruation, which is great for some patients but not others,’ Professor Clancy concludes. ‘Suppressing menstruation takes away substantial autonomy from the patient. It is, for example, nearly impossible to self-administer an intrauterine device and difficult, though less so, to remove one. It feels like we miss every chance we have to listen to patients, which, I imagine, is especially frustrating for nursing that has to prioritise care.’
Mark Greener is a medical writer
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