Period 21: Natural born killers
I was on Slate’s podcast The Waves this week – which was such a treat because I’m a big fan! Between being on The Waves and This Podcast Will Kill You I’ve already knocked off several podcast guest appearances off my bucket list. Cheyna Roth, senior producer at Slate and host, had such thoughtful questions and I was glad to have another chance to also talk about why inclusive language matters and is more scientifically accurate – nice when our ethics and our science lines up, isn’t it?
I’m chugging along on my next book – and in fact issues of inclusive language and scientific accuracy is yet again on my mind. A popular frame for how we talk about reproduction in the uterus is to discuss “maternal-fetal” stuff. There’s “maternal-fetal conflict,” the “maternal-fetal interface,” even just “maternal-fetal health.” And this framing does two things that just don’t work for me:
It’s not representative. “Maternal” is gendered so of course doesn’t represent all birthing people, but also people constantly use the term “maternal-fetal” when they are describing things happening before any of those materials can be characterized as a fetus. Here’s a good layperson description of the stages of development – the being is not officially a fetus until the ninth week of pregnancy, which is typically six-ish weeks after implantation. So we are ascribing earlier materials with a later stage designation – which in our culture also means ascribing it with far greater personhood. (The whole increased fetal autonomy thing of the last few decades is a whole other conversation – The Making of the Unborn Patient and Ourselves Unborn are great books to read on the topic.)
It creates this idea that reproduction is a closed system, dyadic interaction. What do I mean by this? Well for one, in humans there are at least three beings involved here: the people who made the sperm and egg, and then the zygote (and on down the line if it implants, gestates, etc). Not only that, but as sexual reproducers in the act of reproduction we make not only parents, but kin. Consider what a big deal that is – that in birthing a baby we create not just parents but grandparents, cousins, aunts… niblings, siblings, and more. “Maternal-fetal” closes us off to those possibilities.
So now you know as I am data dumping massive quantities from papers on egg chromosomal abnormalities onto the page, my brain is also thinking these thoughts.
Links
The Indian Child Welfare Act has been upheld by the Supreme Court!!! If you aren’t familiar with ICWA you can read more here or check out mentions in previous newsletters of mine.
Bethany Brookshire, author of Pests, has a brand new piece up at Undark looking at spillover – when pathogens in animals go on to infect humans – and what the study of these animals might help us understand to head off the next pandemic.
Ed Yong, author of An Immense World, has written a few great pieces lately – most recently on the snow fly, which has an absolutely wild biology. But I finally got around to reading this piece of his from earlier in May on naming conventions, and it’s an enduring read. Ed shares the problematic history and often colonialist legacy of how it is we’ve come to talk about many animal species, naming them after people who never themselves viewed the animal; who committed atrocious acts of ethnic cleansing; others have names that are explicitly slurs. Audubon himself has a terrible history, so much so that local chapters and the union of the National Audubon Society have renamed themselves. There’s more to it than even this – what does it mean for humans to constantly do this act of claiming and naming? You will need to read it to learn the rest.
Finally, you may have heard that Tori Bowie, three-time Olympic gold medalist sprinter, died of eclampsia in her own home according to the recently-released autopsy report. Eclampsia is the progression of preeclampsia – it is a hypertensive disorder that involves seizures, and without medical help is deadly. All forms of preeclampsia are incredibly serious and are on the rise because covid-19 infections increase their risk. I cannot stress to you how scary and worrying it is right now to think about the health of pregnant people when we have all decided these infections are ok.
We continue to operate in a major Black pregnancy health crisis. As Tianna Madison pointed out on her Instagram, three of the four members of that gold medal winning 4x100 team have had life-threatening health issues associated with pregnancy. Black birthing parents not only face greater risk of miscarriage, they face greater risks to their own lives. As I’ve been reading up more on pregnancy for my book, it’s clear that health inequities and racism influence every single step of the process – from ovulation, to gamete fusion, to implantation, to pregnancy, to birth. Every step.
Weird period fact: natural born killers
Endometriosis is a condition characterized by endometriotic lesions that are present outside of the uterus. These lesions are hormone responsive which is part of why they cause so much pain – spread a whole bunch of endometrial tissue all over your abdominal cavity and then see how you feel when menses and those prostaglandins hit.
There are a lot of ways to think about endo, and a lot of avenues for research to figure out why it happens to some people and not others, why some experience more pain than others, and more. One aspect of endo is that some people think that it is represented by uncontrolled growth – that for some reason endometrial tissue becomes endometriotic when it proliferates and there isn’t some kind of check to keep it from doing so.
A recent study of menstrual effluent between people with diagnosed endo, suspected endo, and controls continues to support the unchecked proliferation hypothesis. Researchers found lower concentrations of uterine Natural Killer (uNK) cells among those with both diagnosed and suspected endo. These cells are incredibly important to endometrial function and the function of the early decidua – that’s what we call the endometrium once it is interfacing with an embryo. Specifically, uNK cells help with decidualization, which is the transition the endometrium makes away from growing and towards changing into a tissue suitable for reproduction. The next question of course is why some people seem to have such depleted populations of uNK cells, and whether there is anything we can do to revive them to put that check back on endometrial growth.
There’s a lot of other stuff uNK cells do that is incredibly cool, but most of it has to do with pregnancy. So you’ll have to wait until the next book to learn more!
Source: Shih, A. J. et al. Single-cell analysis of menstrual endometrial tissues defines phenotypes associated with endometriosis. BMC Medicine 20, 315 (2022).