In 1974, The Lancet published letters debating whether menstruating women give off a toxin that wilts flowers and stops bread from rising.
Not 1874. 1974. The year of the pocket calculator.
The idea had a name, menotoxin, and a respectable father.
Bela Schick published it in 1920.
He is the same Schick as the Schick test for diphtheria.
He noticed that roses wilted overnight after a maid who was menstruating put them in a vase. He ran some experiments with servants, flowers, and bread dough, and concluded that menstruating women release something poisonous through the skin. Other researchers tested blood, sweat, tears, saliva, and breast milk on seedlings. The results conflicted. They were read as support anyway. The 1974 letters ended only when an epidemiologist pointed out that a photograph of a wilted daisy from 1924 and one dead Italian tree were not enough evidence for a claim in 1974.
Pliny the Elder said the same thing in the first century. He wrote that contact with menstrual blood soured new wine, blighted crops, killed grafts, dimmed mirrors, blunted steel, and killed bees. Eighteen hundred years separate Pliny from Schick. The claim did not change. Only the vocabulary did.
Here is why that idea was so hard to kill.
Nobody knew what a period was.
The old theories were not stupid. They were the best available reading of the only thing anyone could see. The Greek physicians thought women built up more blood than their bodies could use, and that the monthly flow was a necessary purge. Aristotle thought menstrual blood was the raw material of the embryo, shaped by semen. Galen folded both into the theory of humors that ran European medicine for over a thousand years. Every one of these explains the blood, because the blood was the only part anyone could observe.
The part that actually matters is invisible.
An egg is released. The structure left behind in the ovary makes progesterone. Progesterone holds the lining of the uterus in place. If no pregnancy follows, that structure shuts down, progesterone falls, and the lining sheds. The bleeding is not the event. It is the receipt for an event that happened about two weeks earlier and left no visible sign at all.
That was not established until 1929, when George Corner and Willard Allen showed that extract from the corpus luteum transformed the uterine lining and sustained early pregnancy. They called the substance progestin. Four teams isolated it in crystal form in 1934. It was named progesterone in 1935.
So the arithmetic is this. Two thousand years of theories about what the blood meant. Ninety seven years of knowing what it is.
Religious and cultural rules ran alongside the medical theories and often outlasted them. Leviticus places menstruation in a category of ritual states that includes men, and sets a seven day period of separation. In 601, Pope Gregory the First was asked whether a menstruating woman could enter a church or receive communion. He answered that she should not be barred, because she suffers it involuntarily and nature causes it, so it is no fault. That is a more accurate statement than most medical writing for the next twelve hundred years. His own successor reversed it within ninety years.
What does any of this cost a patient today?
Three things, and all three are still in the room.
When bleeding is treated as shameful, women describe it inaccurately, or not at all. When menstruation is framed as an affliction, pain gets an explanation before anyone looks for a cause. And when nobody talks about periods, nobody learns what normal looks like. That last one is why a girl whose periods have been heavy since her very first one has no way of knowing that this is unusual, and why bleeding disorders in teenagers are still missed. She has no baseline. Nobody gave her one.
My take.
I did not write this history for the entertainment value, though Pliny provides plenty. I wrote it because the pattern has not stopped, and I recognize it in current practice.
Diagnostic delay in endometriosis is still measured in years. The largest contributor is not imaging technology or access to specialists. It is normalization of pain, by patients, by families, and by clinicians. That is the Aristotelian and Levitical inheritance operating in a consulting room in 2026, wearing a white coat.
We also still cannot agree on what a heavy period is. The research threshold is more than 80 milliliters of measured loss. The clinical definition is bleeding that interferes with quality of life. The public health definition is bleeding over seven days, or soaking a pad more often than every two hours. Three definitions, three different groups of women identified, all currently in use.
Menstrual bleeding received standardized international terminology only in 2011, revised in 2018. Before that, menorrhagia meant whatever the person saying it meant. The menstrual cycle was formally described as a vital sign, to be asked about at every visit, in 2015. Both of those are more recent than the smartphone.
We are better than Pliny. We are not finished.
The bottom line is simple. If your period is heavy, painful, or has changed, that is a finding, not a fact of life. It has a cause, and causes can be identified. Two thousand years of people telling women otherwise does not make it true.
Subscribe
ObGyn Intelligence is free because the work matters. If you want to keep it independent, a paid subscription does that. Share this with a colleague who still tells patients that bad periods run in the family.
References
1. Pliny the Elder. Natural History, Book VII, §64.
2. Schick B. Das Menstruationsgift. Wien Klin Wochenschr. 1920. [CITATION NEEDED — volume and pagination not verified]
3. Ernster VL. Letter. Lancet. 1974 Jun 29:1347. [CITATION NEEDED — verify against journal]
4. Allen WM, Corner GW. Physiology of the corpus luteum. Proc Soc Exp Biol Med. 1929;27:403–5.
5. Allen WM, Butenandt A, Corner GW, Slotta KH. Nomenclature of corpus luteum hormone. Science. 1935;82:153.
6. Simmer HH. Ludwig Fraenkel: ‘spiritus rector’ of the early progesterone research. Eur J Obstet Gynecol Reprod Biol. 1998;83(2):169–74.
7. Bede. Ecclesiastical History of the English People, Book I, Ch. 27. Libellus responsionum, Gregory I to Augustine of Canterbury, 601 CE.
8. Leviticus 15:19–30.
9. Munro MG, Critchley HOD, Fraser IS; FIGO Menstrual Disorders Committee. Int J Gynaecol Obstet. 2018;143(3):393–408.
10. ACOG Committee Opinion No. 651. Obstet Gynecol. 2015;126(6):e143–6.
11. DeLoughery E, Colwill AC, Edelman A, Bannow BS. BMJ Sex Reprod Health. 2024;50(1):21–6.
12. The full history, with verification status marked per source: https://menstria.com/history