Menstruation (with Dr. Kate Clancy)

Menstruation is so much more than a useless byproduct of the reproductive cycle — it’s a dang biological miracle. With the help of Dr. Kate Clancy, a professor at the University of Illinois and author of Period: The Real Story of Menstruation, this episode dives deep into the misconceptions, stigmas, and hidden truths about menstruation. Uncover the true purpose of periods, debunk the idea of a ‘normal’ period, and explore how environmental factors and personal experiences can impact menstrual cycles. We touch on premenstrual dysphoric disorder, PCOS, and endometriosis, along with the stigma associated with menstrual blood and why efforts to give menstrual products to girls in the global South are misguided. Also, retrograde menstruation. You’ve been warned.

Pick up Kate’s book, “Period: The Real Story of Menstruation.”

Video version:

Period Stigma: Misconceptions & Hidden Truths of Menstruation w/ Kate Clancy – Taboo Science S3 E9

Menstruation is so much more than a useless byproduct of the reproductive cycle – it’s a dang biological miracle. With the help of Dr. Kate Clancy, a professor at the University of Illinois and author of Period: The Real Story of Menstruation, this episode dives deep into the misconceptions, stigmas, and hidden truths about menstruation.

Citations and further reading:

Example of the rhetoric menstrual health organizations use about people in developing countries (this image is labeled “The Problem” on The Cup Foundation):


Ashley: Imagine a 12 year old girl. Her parents are divorced and living a few hundred miles apart, and she spends summers with her father. She’s done that for years. Going to movies and amusement parks and watching cable, which she doesn’t have at her mom’s, and just doing the kinds of things a kid does when school isn’t on their mind.

Ashley: But one afternoon, about a week before she goes back to her mother’s house, a large dark smudge appears in her underwear. She’s shocked and a little scared, even though she knows that this must be the period she’s heard is coming. She’s mortified to tell her dad, and she’s hundreds of miles away from her mom, the only person in her immediate family who’s been through this before.

Ashley: What would you do? In the case of this 12 year old girl who, hi, it’s me, I was that 12 year old girl, she hid the fact that she’d had her first period. For days, she fashioned pads out of toilet paper. The blush still rises to my cheeks when I remember my dad saying, who’s using all the toilet paper lately? But in the case of other girls, whose now grownup women versions told me stories about on Twitter and in group chats, they did other things. Ignored it and hoped it would go away or quietly took their mom’s menstrual supplies so they wouldn’t have to tell anyone.

Ashley: I know people in their thirties who still haven’t told their parents. Or enviably, some of these people had the kind of adult support that let them just shout through the door. Hey, I just got my period! And calm, non-judgmental adult help arrived.

Ashley: There are a lot of reasons a young girl would wanna hide her period. We tell girls that a period makes them a woman, which is a lot of responsibility for a tween girl who probably still needs her childhood stuffed animal to sleep.

Ashley: We also say periods are dirty, that they make women crazy, that they’re why only men should be in positions of power.

Ashley: None of these things are true. Periods are a goddamn miracle of biology. And today we’re gonna find out why.

Ashley: I’m Ashley Hamer, and this is Taboo Science, the podcast that answers the questions you’re not allowed to ask.

Ashley: As a tween, what I learned about the menstrual cycle goes like this. Over a few weeks, the uterus starts padding its walls with tissue to prepare for a fertilized egg to implant there. One of the ovaries releases an egg, it travels down the fallopian tube into the uterus, and it waits to be fertilized by sperm.

Ashley: If it’s not fertilized, the uterus is like, Ugh, we failed out with you. And it sheds that lining, which comes out of the vagina as period blood.

Kate Clancy: You’ve got the common understanding down. While generally speaking, that narrative is not so far off, there is a lot more dynamic action happening through that whole menstrual cycle.

Kate Clancy: My name is Kate Clancy. I’m a professor of anthropology at the University of Illinois, and I mostly study how environmental stressors affect menstrual cycles.

Kate Clancy: But really the purpose of menstruation isn’t just like to get rid of stuff, if pregnancy doesn’t happen.

Kate Clancy: And that’s sort of where one of the biggest assumptions often lies, is that it’s sort of this useless byproduct of the fact that we have to start over each cycle. It’s not that that’s wrong, it’s that like, we contain multitudes.

Kate Clancy: The biology is capacious in the way that it repurposes and does multiple things that have multiple meanings. Menstruation has at least two other purposes. One is to actually heal the endometrium, um, to allow it to regrow for the next cycle. And the other is to give it some practice at all of that cool tissue remodeling that it’s doing. So, you know, maybe you’re not pregnant that cycle, but it’s making, you know, the endometrium even more prepared for doing so in a future cycle.

Ashley: Wait, practice? I can’t imagine human tissues needing to practice anything. How does, how does that help? What, I don’t understand.

Kate Clancy: So there’s lots of things our bodies get better at over time, right? I mean, the body needs to practice getting better at running. Um, the body gets better at cervical ripening. You know, the, a first pregnancy, usually labor takes a lot longer than second and third and subsequent labors, and that’s because, you know, once the body has a little more practice doing all of that with dilation of the cervix and with responding to, you know, prostaglandins and everything and like doing all of the contracting, it needs to do, it kind of gets better at that after the first try.

Kate Clancy: So it’s actually not uncommon that just like our brain needs practice to get better at playing piano or learning to read that our body needs practice to get better at various types of processes as well.

Ashley: Which may be why miscarriage rates for people in their teens are about the same rate as people in their mid thirties. Their bodies haven’t practiced enough and they aren’t as ready to carry a child as they would be later. We talk about girls becoming women when they have their periods, and there’s a weird subset of society that fetishizes the good old days when girls married in their teens and started popping out babies.

Ashley: But it’s not really what we’re built for. Saying a girl is a woman because she’s had her period is like saying I’m a triathlete because I bought a bike. There’s a lot more that has to go into it.

Ashley: Another part of the common understanding of menstruation involves ovulation. I had this idea that your ovaries were just full of eggs, like an ovulation gumball machine, and every month one would pop out and roll down the fallopian tube to wait for fertilization. In reality, the eggs we’re born with aren’t quite eggs yet.

Ashley: They’re immature. They’re called oocytes, and they each live in their own little fluid sac called a follicle. Early in the menstrual cycle, hormones act on the follicles to get these junior eggs to start maturing. Eventually the story goes, one egg is chosen as the best egg inside what’s called the dominant follicle.

Ashley: The egg pops out and waits for the sperm to ride over on its little sperm horse, bravely climb up the tower and rescue it like the princess it is. But it turns out that’s not quite how it works. The selection process within the ovary to choose the number one best egg?

Kate Clancy: That is like Hunger Games level selection. It’s also continuous, so there’s waves of development that are happening continuously as opposed to just like recruitment to a spur, a single egg.

Ashley: And the only reason we know this is because farmers wanted to know when their animals would reproduce.

Kate Clancy: That happens across many different species. And the agricultural industry has been really interested in understanding the reproduction of a lot of domestic species for a really long time because, you know, farmers need that because the agricultural industry needs it. Because capitalism, right? Like they wanna make money on their work product, which is, how many cattle can I make? Can I time things the way I want? Et cetera. So follicle waves are something that were observed in domestic animals for quite some time, using ultrasonographic methods, so doing ultrasound.

Kate Clancy: So we, we’ve known that this is common across other mammals, but somehow there’s always this idea that like humans are a little bit different and a little bit more special. And so we continue to have this narrative of this single wave and this single ovulation. And thanks to the work of Angie Baerwald and Roger Pierson, we now know that’s not the case.

Kate Clancy: And it’s because of their incredibly tireless efforts and Angie’s dissertation research.

Ashley: Part of the reason Roger and Angie could make this discovery was technology. Before their research, you can only look at an ovary by cutting it open. Roger happened to have access to one of the first real-time ultrasound units in North America, so he was able to identify these waves in domestic animals.

Ashley: The bigger reason was dogged determination and hard work.

Ashley: To discover this process in humans, Angie performed daily transvaginal ultrasounds from one ovulation to the next on about 100 women. As Katie writes, she scanned up to a few dozen ovaries every day, seven days a week, for months. She counted and measured every single follicle in every single ovary.

Kate Clancy: And when you’re going every single day, so you’re seeing which ones are growing, which ones are shrinking, you know, you’re able to actually document what’s happening with the follicle wave. So that’s where she was able to figure out that there are two or three waves per ovulatory cycle, and that there’s even different major and minor waves. And this is probably why in humans we sometimes have multiple ovulation, is it’s not that necessarily there are two dominant follicles that erupt from the same wave, but sometimes even from two different waves.

Ashley: This has huge implications for all sorts of things. Like birth control.

Kate Clancy: Because if we don’t actually know when ovulation is timed as well as we think we do, then that means that certain types of contraception, like the Sunday start method for birth control, um, might actually allow an egg to ovulate before you get started on contraception, which is probably not a good idea since you’re trying to prevent that.

Ashley: If you’re not trying to prevent that, it has implications for you too.

Kate Clancy: It has implications for I V F and for people who are trying to preserve fertility through cancer treatment because it means that you maybe have multiple opportunities in a single cycle to try to preserve some eggs.

Ashley: And if you’re a fraternal twin or a parent of twins, it definitely has implications for you.

Kate Clancy: It changes how we understand multiple pregnancies. People who are pregnant with twins that are not identical, um, that they might not arrive from, you know, two eggs ovulated at the same time.

Kate Clancy: And in particular, there are times where, you know, fraternal twins are actually really different in size and seemingly gestational age. And it’s probably because they are different gestational ages.

Ashley: Just in case you’re like, wait, gestational age? That’s how long a baby has been in the womb. 39 to 41 weeks is considered full term, anything before 37 weeks is considered premature. That kind of thing. So twins could be born at the same time, but several weeks apart in gestational age. Kind of mind blowing, right?

Ashley: And finally, it has implications for literally anyone having a baby.

Kate Clancy: The final consequence of this, which to me is one of the most frustrating, is that we calculate gestational age by last menstrual period.

Kate Clancy: So if you have your period and then two-ish, three weeks later you ovulate and then one-ish week after that is when implantation occurs. But people are always marking gestational age from that last menstrual period and not accounting for all that variability and follicular wave wavelength, timing of ovulation, timing of implantation, your reported gestational age could be different than your actual gestational age.

Kate Clancy: And you know, ultrasound telling of gestational age is imperfect. So, you know, somebody could be guilt tripping you into inducing your pregnancy inducing labor at say, 39 weeks, which is a very common practice now, on what is like a 37 week fetus, which carries far worse implications for the fetus than if you actually let the baby be born, you know, closer to their appropriate gestational age.

Kate Clancy: [music]

Ashley: Not only is there no normal timing for ovulation, there is no normal menstrual cycle. The stuff we’re taught is just a mathematical average and the vast majority of menstruators don’t play by those rules.

Kate Clancy: normal used to mean, a description of the functionality of something.

Kate Clancy: So what is the normal kidney? Well, the normal kidney does X, Y, Z functionally. Increasingly with some of the eugenics moves that happened to start to think about, um, physical characteristics in terms of desirable and undesirable traits. We started to use more statistics to apply to groups of people and started to understand what was called a normal distribution, where you look at the frequency of say height, and you find if you look, if you measure a whole bunch of people, you’ll find there’s a, um, an average height.

Kate Clancy: And then if it is a normally distributed, you kind of find a curve on either side, a bell curve, right? That looks even on both sides. And so then the idea is like what’s within about a standard deviation of that norm, of that average is what constitutes normal. And then you can fall multiple standard deviations outside of the range of normal.

Ashley: Standard deviation is a measure of the amount of variation there is in a set of data. It’s mathy, but basically that bell curve is divided into sections, and the further away your section is from the middle, the less normal you are.

Kate Clancy: Then we started conflating normal with healthy and we started assuming that if you fit within the norm, that must mean you’re healthy. If you fit outside the norm, that must mean you’re diseased. So all of these things together, right? These ways of trying to classify desirable as average, desirable as normal, desirable as healthy, mean we have this very conflated term that means a whole bunch of things, and that we’re not always clear what we mean, and we use that word normal. So then you enter looking at menstrual cycles. And if you actually measure a menstrual cycle, unlike looking at like what you see in a medical textbook or health textbook, it does not look anything like what we see in a textbook.

Ashley: Kate’s lab found this themselves by studying people’s hormones throughout the menstrual cycle. If you ask a medical textbook, or in my case a reference page from the Society for Endocrinology, the ovulation process I just described starts with a rise of follicle stimulating hormone, or FSH. As the strongest follicles grow, they produce estrogen and reduce the levels of FSH, which kills off any straggler follicles. By now, we’re in the middle of the cycle. Those estrogen levels hit their peak and trigger the production of something called luteinizing hormone. Luteinizing hormone is what gets the egg to finally ovulate, which leaves behind an empty follicle that scientists call the corpus luteum. This kind of follicle corpse thing secretes progesterone to prepare the uterus for implantation.

Ashley: That’s where all that tissue builds up that will potentially come out in your period. If an embryo forms, it secretes something called human chorionic gonadotropin, or HcG, to tell the corpus lutetium to keep on pumping out progesterone and keep the womb nice and hospitable.

Ashley: HcG is the hormone that pregnancy tests detect. If there’s no embryo, the progesterone stops pumping and all that tissue is shed into your tampon pad, diva cup, or brand new swimsuit.

Ashley: So FSH rises, then estrogen rises and FSH drops, estrogen peaks and triggers luteinizing hormone, you ovulate, progesterone rises, and then if you’re not pregnant, progesterone drops.

Ashley: At least that’s what the quote unquote “normal” menstrual cycle looks like. But when Kate’s lab studied tons and tons of menstrual cycles, normal isn’t what they found.

Kate Clancy: So you have some people who have like two little peaks of estrogen and then a second wave in the second menstrual cycle. You see kind of like a. A low amount of estrogen and then like the second half is higher. Um, and these are all within ovulatory cycles, which we’re able to confirm because of the fact that in all of these cases, I’m talking about individuals where they have a progesterone rise in the second half of the cycle.

Ashley: Remember, progesterone rises because the egg was released. It means you ovulated.

Kate Clancy: So even across all of these ovulatory healthy cycles, um, they were not normal. So we tried to change the way we do the statistics in our lab and instead of calculating norms, because when you do that with all sorts of non-normal cycles, it actually ends up looking like that bell curve a lot of the time, or you end up looking towards a mean that looks like what you see in the textbooks. But when we did what’s called geometric morphometrics with different landmarks through the menstrual cycle, we were able to see that in one of our samples, at least, of over a hundred menstrual cycles across rural Polish and Polish American people.

Kate Clancy: We were able to see that there are at least three discrete groups, three discrete patterns of estrogen and progesterone through the cycle. And you know, ideally as we are able to apply this method to other data sets, we might see different ranges of normal.

Kate Clancy: So, what we were finding is not that we’re disrupting the norm of the one and showing you there are now three. What we’re trying to do with our statistics is show you’re going to find sample specific numbers or sample specific groups. It’s not our three are the same three.

Kate Clancy: It’s that depending on your population and the environmental factors that might affect them, their first age at menarchy, their lived experience and more, we’re gonna see potentially really different things.

Ashley: When you consider that different people have wildly different menstrual cycles compared to what textbooks say is normal, it’s no wonder that their experience of menstruation is different too. Not everybody experiences those classic PMS symptoms: irritability, mood swings, bloating, cramps, an intense desire to buy a giant Hershey Symphony bar with the little toffee pieces in it.

Kate Clancy: It’s hugely variable between people and over the course of people’s lives. So this is one of the things that it’s, it’s like tricky in some ways to talk about because, You don’t wanna like give in to the people who are like, these ladies be so emotional. And any of that rhetoric.

Kate Clancy: But at the same time, there are subsets of people who intensely experience the hormonal fluctuations of their menstrual cycle.

Kate Clancy: When you study this, prospectively, so not just like asking in the past, Hey, have you ever been irritable before your menstrual period? Or, hey, have you ever felt bloated or whatever, you know, to which any of us can probably say, yeah, at some point, we absolutely have.

Kate Clancy: When you measure this prospectively, meaning somebody keeps a diary every single day through a menstrual cycle, and then you look at the evidence, people who have like a really profound shift in, in mood and behavior and cognitive symptoms is really only about 6% of people who menstruate.

Ashley: Now, that’s not to say only 6% of people who menstruate experience any mood swings at all. This is significant mood swings like you’d see in premenstrual dysphoric disorder, a really severe form of PMS with a list of symptoms that honestly looks a lot like depression: hopelessness, lack of interest in activities you normally enjoy, suicidal feelings.

Ashley: It’s not easy to diagnose, but it is definitely easy to notice in your own cycle. That’s what scientists see when they have people keep a diary of their symptoms.

Kate Clancy: What we’re looking at is potentially a condition where people are, for some reason, much more responsive to or aware of their hormonal fluctuations and therefore it affects them.

Kate Clancy: For the other, what, 94% of the world. There’s still some variability. There’s people who could say, I couldn’t tell you where I am and my menstrual cycle, if it weren’t for an app, who are surprised by their period whenever it comes, ’cause they’re not experiencing variation. And there’s some people who kind of know when it’s gonna come.

Kate Clancy: And again, it varies through the life course. So like I had really no predictive power at all for the first 15 years I menstruated, I’d say.

Kate Clancy: It wasn’t until sometime in my thirties that I started noticing some mood shifts where I would just be ridiculously angry for three to five days before my period. Like everything set me off. And then, you know, I’d get my period and then go, Ooh, that’s why I got really mad. You know, like that kind of a thing.

Kate Clancy: Um, and then that’s been going away again in the last year. It’s not happening to me anymore. So, you know, it kind of depends on estrogen to progesterone ratios, our own responsiveness. Our own lived experiences. People with a history of sexual trauma or physical trauma in childhood have different downstream experiences of their cycle.

Kate Clancy: So, I know it’s a very long answer, but it, the, the short version is it’s complicated.

Ashley: But here’s what we never talk about when we talk about the annoyances of PMS. That time of the month can bring good things too. I found a 20 year old study that asked college students about their experiences of menstrual joy. They got a survey where they had to indicate which positive experiences they had in the lead up to, during, and after their periods. While all of the positive experiences on the list were more common when they weren’t menstruating, obviously, the highest rated experiences during the premenstrual phase were increased sexual desire, feelings of affection, and self-confidence.

Ashley: And the highest rated experience during menstruation was feelings of affection. I also love that they asked the participants for their reactions to the menstrual joy questionnaire itself.

Ashley: A quarter of them believed that the title was quote, sarcastic or ironic. Fair. So yeah, minimal research on menstrual joy, but there is some research on menstrual relief.

Kate Clancy: If you experience a lot of premenstrual symptoms, then the period is actually a time where you’re like, oh God, finally. Like, in cycles where I’ve been feeling very irritable in the few days before my period, and I. am suspecting that these things are related, I am usually so happy like that I get my period. ‘Cause I’m like, oh gosh, that horrible couple of days is over. Right. I’m refreshing and starting over.

Kate Clancy: If anybody has ever worried they might be pregnant, and they get their period, there is joy and relief in experiencing that period.

Kate Clancy: Another one is that, um, you know, there was this amazing qualitative paper I read from just a couple of years ago. And it was looking at non-binary and trans experiences of menstruation.

Kate Clancy: And there’s this overarching assumption that because of gender dysphoria, anyone who doesn’t identify as a woman and has a period is just automatically going to hate periods. And it’s much more complicated than that. There are absolutely people for whom their dysphoria is increased when they get their period.

Kate Clancy: But there are some people for whom they’re like, yeah, that’s right. Like, I’m gonna disrupt your gender norms. And they have a different experience of it where they’re like, that’s right. I can be someone who menstruates and also be this dude. Or people who, uh, you know, there’s a person in this study who, if I remember correctly, had experiences with P C O S.

Ashley: That’s polycystic ovarian syndrome, and we’ll talk more about that later in the episode.

Kate Clancy: So every time that person got their period, it felt like a victory. ’cause I was like, yeah, I’m getting victory over my P C O S because P C O S is often characterized by amenorrhea or not getting your period.

Ashley: PCOS isn’t the only reason someone might not get their period, obviously. There are a lot of environmental factors that can interfere with the menstrual cycle. Things like chronic stress or being infected with a virus like COVID-19, or too much exercise. At least that’s what I thought. I’ve run a lot of marathons and I know how female athletes can sometimes exercise so hard that they stop having a period.

Ashley: It’s called the female athlete triad, the combo of no period, low energy availability, and decreased bone mineral density. But too much exercise isn’t the whole story.

Kate Clancy: compromising your menstrual cycle in some way or experiencing major shifts in your menstrual cycle isn’t possible with exercise alone. You have to not eat enough to meet your exercise.

Ashley: Female athletes face conflicting pressures, especially in sports that require thinness like running and dancing. On the one hand, they need to train hard and build muscle to be good at their sport. But on the other hand, both their sport and society at large tells them they need to stay thin.

Ashley: So while a workout might burn 2000 calories that you need to eat back to fuel your muscle growth, diet culture says that carbs will make you fat and fruit has too much sugar and salads are great, but make sure the dressing’s on the side. So they don’t eat enough and then they lose their periods, and then they think they’ve done something wrong when they’ve done everything they were told to do.

Kate Clancy: If you’re not paying attention to eating enough, Yeah, exercise is going to mess you up, but we don’t understand it as a disease of undereating or a disease of undernourishment or of eating disorders, which really is what it often is.

Kate Clancy: I

Ashley: Instead, the medical establishment is fully preoccupied with how overnourishment or being overweight affects the menstrual cycle, especially when it comes to fertility. Women are told that if they wanna get pregnant, they need to drop pounds to get to a so-called healthy weight.

Ashley: But as Kate writes, there is a ton of research that shows one, that losing weight doesn’t really help with fertility, and two being underweight is way, way worse for your fertility than being overweight.

Ashley: One study showed that people who were 20% heavier than their normal weight were twice as likely not to ovulate, but people who were 15% lighter than their normal weight were five times as likely not to ovulate.

Ashley: Our obsession with weight loss at any cost can do real damage.

Ashley: The other main issue people blame on weight is a condition called polycystic ovarian syndrome or PCOS. To be diagnosed, you need two of three symptoms: polycystic ovaries, that is ovaries with a bunch of large unerupted follicles, higher than normal testosterone levels, which can either be measured directly or judged visually by abnormal hair growth and missed periods or ovulation.

Ashley: PCOS is associated with insulin resistance, which can be caused by being overweight. again, that’s not the whole story.

Kate Clancy: polycystic ovarian syndrome is a metabolic disease, but it is a massive oversimplification to say that body weight is causal of PCOS. It’s an underlying metabolic disturbance that can both increase weight and increase polycystic ovaries.

Kate Clancy: That is the cause. Right, which is so, so it’s not the same thing. It’s saying there’s a correlation between two phenomena that have a common origin as opposed to saying it’s obesity that’s causing it.

Ashley: Cultural stigmas have a big impact on what gets studied and what research people pay attention to. Obesity is one of those stigmas, but of course so is menstruation.

Ashley: Kate told me about one thing that I couldn’t believe I never considered: blood tests using menstrual blood. I mean, I’ve done a lot of blood tests and not once has blood come from downstairs, and that could be due to stigma.

Kate Clancy: I do think that we have, um, missed out for years on seeing menstrual effluent as having a lot of diagnostic potential.

Kate Clancy: So we do a lot of blood tests where it’s like you take one peripheral blood measurement and then you use it to tell somebody about what’s happening in their whole body. Well, there’s like a blood brain barrier, so circulating levels in your peripheral blood don’t necessarily have any relationship to whatever’s circulating in your brain.

Kate Clancy: But also there’s a lot of local variation in blood and menstrual effluent isn’t the same as just blood. There already have been some studies that have shown different properties and different things that you can find at different phases of the cycle from peripheral blood.

Kate Clancy: And then, during menses, peripheral blood versus effluent is different, which means that we might get better at developing non-invasive methods for measuring and understanding different things happening inside the body.

Kate Clancy: So, as one example, endometriosis is an illness where you have endometrioid lesions of what we often presume is endometrial tissue that is in your abdominal cavity.

Ashley: Endometrial tissue is the tissue that lines the uterus. It’s the thing that thickens to prepare for an egg and sheds when you have your period.

Kate Clancy: It finds different parts of your body to go in and invade and stick to, and then it hormonally responds just like endometrial tissue, which can cause a lot of pain, and also potentially, excess bleeding. The only way to officially diagnose somebody with endometriosis is to do laparoscopic surgery and surgically stage them. So do the surgery and look for lesions, and then the amount of lesions you see are how you surgically stage them. And you say you have endometriosis stage, whatever. So it means you have to have surgery to ever get an official diagnosis of endometriosis, which is part of the reason it takes 10 to 15 years to diagnose it.

Kate Clancy: If you were able to wear a menstrual cup on day two of your menstrual cycle for two to four hours, decant that in a little tube, and bring that in, wouldn’t that be way better, in terms of being able to measure biomarkers and be able to distinguish fairly reliably between folks with endometrioid lesions versus not?

Ashley: This is wild. According to a 2018 study led by Peter K. Gregerson, menstrual blood from people with endometriosis is different than menstrual blood from people without it. Something I did not know that this study explains is that almost all women, with or without endometriosis, experience quote, retrograde menstruation. is period blood flowing back up the fallopian tubes and into the abdominal cavity.

Ashley: Oh, you didn’t know the fallopian tubes weren’t connected to the ovaries and instead catch the eggs like they’re in an arcade game. Yeah. Glad it could blow your mind a second time. Anyway, cells in the menstrual blood of people who develop endometriosis seemed to have the ability to differentiate into endometrial tissue. So that usually harmless blood backwash turns into tissue where it shouldn’t be. Absolutely wild stuff. Anyway, that’s why period blood could be a great way to diagnose endometriosis way earlier than we can right now.

Ashley: And yet the thought of bringing in a sample of period blood to your doctor might be just above bringing in a stool sample on the list of gross things you’d rather not have to do. Menstrual blood is seen as dirty, way dirtier than regular blood. that idea influences some very well-meaning efforts to help menstruators in various parts of the world.

Kate Clancy: There’s sort of this very capitalist intervention model, which is, let’s get more pads or cups or whatever in the hands of, especially people from the Global South and that will fix their problems in terms of access to materials, access to bathrooms, privacy, water access issues, being able to get to school, you know, because there are these narratives that like periods are why girls don’t go to school.

Kate Clancy: One, a lot of those things turn out to not to be true. So like periods are not what are keeping girls from gonna school. There’s a lot of other bigger things that are keeping girls from going to school. But that’s not to say it’s not important to then address issues of menstruation. But the underlying assumption, the other reason that it’s so important we address menstrual hygiene is that menstruation is dirty. And that by not giving people access to say disposable products or other types of, by the West prescribed appropriate products, um, that they’re increasing risk of various types of disease by using, you know, homemade disposable stuff.

Ashley: What do people in the Global South use if they don’t use store-bought pads and tampons? These menstrual health movements often make it seem like it’s just whatever they could find on the floor, leaves, sponges, newspaper, mattress stuffing.

Ashley: In fact, but most people use cloth. It’s inexpensive, washable, and reusable. I could honestly imagine a startup advertising cloth pads to me on Instagram as a sustainable alternative to disposable if they haven’t already. But because these are homemade, and probably more importantly, not what anyone in the West would use, they’re assumed to be dirty and a health risk.

Ashley: But the research doesn’t really bear this out.

Kate Clancy: In a randomized controlled trial that did nothing, offered menstrual cups and offered menstrual pads, they looked at the hygiene outcomes of these different groups in, I wanna say it was like 12 schools in Kenya or 30 schools. I mean, it was like a very large sample size.

Ashley: it was 30 schools in rural western Kenya. 10 schools got menstrual cups, 10 schools got menstrual pads and 10 schools got nothing and just had the girls do whatever they’d usually do. There were 644 adolescent girls in all.

Kate Clancy: And what they found over months and months of analysis is that, um, the things that they expected to improve

Ashley: That is, reproductive tract infections. Things like bacterial vaginosis.

Kate Clancy: Those outcomes that they thought to improve didn’t improve. The interventions decreased sexually transmitted infections. And why is that? Well, these same authors also have done some qualitative work and shown that when you don’t have extra cash to buy menstrual products, you engage in sex work and transactional sex in order to get a little extra money.

Kate Clancy: So what they were doing was reducing their need for sex work. It wasn’t menses that wasn’t hygienic, it’s sex work that wasn’t hygienic. So really the intervention should be, how can we provide more condoms or more education around sexually transmitted infection, not, you know, we need to give people Always Infinity pads instead of the homemade pads that they use.

Ashley: In fact, the thing that keeps girls in the Global South from having access to clean menstrual products is stigma. If you need to wash a reusable pad, but you need to keep it hidden from view, it’s not gonna dry well, and it could become a haven for bacteria.

Ashley: That’s a reality that a lot of girls face.

Ashley: My 12 year old experience in California is certainly not in the same league as a 12 year old in rural Kenya, but the cause was the same. I didn’t know much about periods, but I did know that I had to keep mine a secret.

Ashley: I knew that it was better to suffer through it than to face the embarrassment of telling my dad. A man, a member of society that must be protected from the ills of the female body.

Ashley: There are a lot of things we miss out on when we make menstruation a taboo, not just adult support for 12 year old girls, but understanding, empathy, and freedom.

Kate Clancy: What I really hope is that thinking about something as mundane as a menstrual cycle, something that half of the population experiences 400 times in their lives that’s years of a person’s life, right? If we could put some attention on this mundane process that is often so secretive and hidden and stigmatized and ask, what would it look like for people with these experiences to be able to just move around in the world freely, and with support and accommodation?

Kate Clancy: I think that opens up a bigger disability justice conversation about lots of body variability, about neurodiversity, about gender variability, about physical differences. And it allows us to say, well, what are we doing that it is so hard to be out in public, and not be a perfectly conforming, very narrow definition of normal person that having any step away from that normality makes it harder to exist in the world.

Ashley: Thanks for listening. Huge thanks to Kate Clancy who made me do a little celebration dance when she said yes to my interview request. Her fantastic book is called Period: The Real Story of Menstruation, and you can find a link to pick it up in the show notes.

Ashley: Kate had a lot more to say about iron and syncing cycles and menstrual huts, and this episode is already longer than I’d like it to be. So if you’d like to read more about all of that, definitely sign up for the newsletter. There’s a box for your email right on the website at

Ashley: Science is written and produced by me, Ashley Hamer. The theme was by Danny Lopatka of DLC Music. Episode music is from Epidemic Sound. If need music for a project, use my referral link. It’s in the show notes and it’ll help out the show.

Ashley: The next episode, we’ll be a rerun because I will be at podcast movement. If you’re going, be sure to check out my panel on video podcasting on Tuesday and stop by the Descript booth to say hi. I will give you a Taboo Science sticker.

Ashley:  But the next episode is one of the most popular in the back catalog and it will be fully remastered. So do tune in next time. I won’t tell anyone.