Humoral Medicine | Pregnancy, Birth, and Breastfeeding in the Middle Ages

Today we’re going to learn why swaddling prevents grandma from freeze-drying her newborn grandbaby, among other verified humoral medical facts. Warning, if you’re squeamish about bodily fluids (or sex) then this probably isn’t the article for you.

The Theory

Humoral theory is a framework for understanding the human body that persisted for at least 2000 years. Its origins were in the ancient Mediterranean world with Hippocrates in the fifth century BCE and Galen in the second century CE being credited with the form the theory took throughout medieval Europe. Many ideas that were grounded in humoral theory, especially those around infant care, persisted into the 20th century– and we still use it today when we refer to “catching a cold”.

But keep in mind that very few people in the middle ages would have had the care of a physician or surgeon trained in humoral medicine, and even fewer people would have used one for pregnancy, birth or infant care. The majority of people relied on laywomen, most often the matriarch of the family, to deal with health care, and they tended to work with local herbal folkways and natural magic rather than humoral medicine.

The Humors

Humoral theory posits that the human body is composed of four humors, the word is derived from the Greek χυμός chymos (which translates to juice). they are blood, yellow bile or choler, phlegm, and black bile. Most of us are aware of blood, phlegm, and yellow bile, we’ve been cut, had a sinus infection, and experienced vomiting and diarrhea– but black bile, what’s that?

Black bile may be attributed to necrotic wounds or blood clots. But as someone who lived for over ten years with an autoimmune condition but without access to healthcare, let me assure you that if you vomit long enough and hard enough, you’ll discover black bile when you’ve run out of yellow. (Do not recommend. Oh, and thanks Obama.)

Egerton 2572 f. 51 Volvelle, England, c1486. British Library.

Each humor had many associations but to keep it simple, we’re going to focus on temperature and humidity.

  • Blood is hot and wet
  • Yellow bile (choler) is hot and dry 
  • Phlegm is cold and wet
  • Black bile is cold and dry

To explain the different sexes and changes with age, it was believed that women were colder and men were warmer; the young were moist, the old dry. It was thought that men and women had the same genitals, but the coldness of the female sex caused the penis and testicles to be inverted in a female, and the dryness of old age caused wrinkles.

Diagram showing that females are inverted males. Source: Wellcome Collection

Humoral Medicine

In order to have good health, the humors need to be in balance. Then as now, prevention is the best medicine, and a physician would, after determining the unique humoral make-up of a patient (sanguine (blood), choleric (yellow bile), melancholic (black bile), or phlegmatic (phlegm)) prescribe dietary and lifestyle rules to help keep the body in balance.

Below are anthropomorphized representations of the four humours, source: Wellcome Collection.

But when prevention failed and disease was present, the goal of the physician was to get rid of the excess humors causing the imbalance: fever with sweating: obviously too much of the hot and moist humor of blood, therefore, bloodletting was prescribed (and this does reduce a fever but do not attempt). Stomach pain? Too much yellow bile required purging through emetics, laxatives, or enemas. Other treatments included intentional blistering through topical preparations. But not all humoral treatments were horrible: they also included massage with special oils and herbal baths. 

An illustration of a medieval noble taking his bath and being attended to by servants. Codex Manesse, 14th century CE, Zurich, Switzerland (Wikipedia)


Excess humors could build up anywhere in the body, including the reproductive organs, causing all kinds of diseases throughout the body. For sexually active people, regular sex was advised to expel excess humors. For men and women this required regular orgasms (in the two seed theory, women needed to orgasm to become pregnant). In the middle ages, sex in marriage was considered so important to health and happiness that women could divorce husbands that failed to perform. 

Unfortunately, there was no DIY solution, masturbation was considered not just sinful but unhealthy, as it was likely to lead to a humoral deficit.

Loss of vital humors. A grave imbalance.

But what about people who were sexually mature but not sexually active for whatever reason? Like clerics who took a vow of chastity. How were they to expel excess sexual humors? Become vegetarian. Meat, as a product of sexual reproduction and live birth, was believed to increase carnal lust (note the root of carnal is carne which means flesh, i.e meat), so celibate individuals were discouraged from eating meat (and really, discouraged from eating much at all) to reduce the build-up of sexual humors and therefore the need for sex. (This is rubbish, as any vegan will tell you.)


Infertility or miscarriage was often explained by a woman being too cold for seed (semen) to grow or too wet for the products of conception to stick. The treatments for this would include dietary and lifestyle changes to put the cold and wet humors into better balance with the hot and dry humors. For example, eating more hot and dry foods- not necessarily a description of the temperature or moisture content of the food itself- for example, kale is hot and dry but lettuce is cold and wet. Basically, you needed a physician to tell you what to eat. #BillableHours

During pregnancy, it was believed that the fetus didn’t have a soul until after the fourth month (around the time the mother can feel fetal movement, known as the quickening) before which time miscarriage was considered more likely. In the Trotula it is explained that a pregnant woman who is in need of bloodletting for her own health, shouldn’t be bled until after the fourth month to prevent the risk of miscarriage,

“but when the soul is infused into the child, it adheres a little more firmly and does not slip out so easily”.

Today it is estimated that 80% of miscarriages occur in the first 13 weeks, and around one in four pregnancies will end in miscarriage, often before the person realizes they are pregnant. If you have had a miscarriage, you are not alone and it was not your fault.

It was believed that women had influence over the sex of her offspring. Women who wanted to conceive a male were instructed to lie on their right side after sex, so the seed could be closer to the liver which they believed was the source of the body’s heat and blood in order to produce the warmer male offspring. For the record, temperature-dependent sex determination is a thing in biology for reptiles, not for humans.

For those that don’t know, male sperm is responsible for the sex of offspring: female eggs are all x chromosomes, while male sperms contain x and y chromosomes; x and x create female offspring and x and y create male offspring. Biological sex is a binary (male, female) not a spectrum; and though associated, it’s different from gender (man/boy woman/girl, etc) which is culturally constructed. But that is a subject for another time. Update: If this subject interests you, I recommend Dr Debra Soh’s book The End of Gender.


Humoral heat was also believed to influence the length of gestation. A woman with an abundance of hot humors might bake that bun to full term at only seven months rather than the nine to ten of a normal colder woman. Is this true? Absolutely not. And it’s not really clear if physicians at the time thought it was really true either but it’s a convenient cover for an illegitimate birth and authors/physicians needed patrons (just like I do, but clearly, I won’t lie about the facts of biology to curry favor).

At the other extreme, a cold climate or season might be the reason for a pregnancy going post-term:

“this last condition happens to a young woman giving birth in the winter when naturally she has a tight orifice of the womb, made more so on account of the coldness of the season, for she is more constricted by the coldness of the air.”


To induce labor, it was recommended to give the pregnant woman a rub down in “hot” (humorally hot) unguents:

“such as oil of laurel and oil of linseed and goose or duck or hen’s grease. And let the anointing be done from the navel down with the above mentioned hot unguents.”


Again, this isn’t accurate based on what we know of pregnancy today but a deep tissue massage might help a heavily pregnant person to relax and soothe sore muscles, which is always a good thing. 


Taking the baking analogy a bit further: when a baby is born it’s brimming with warm, moist humors, it’s like a cookie right out of the oven that needs time to set before it’s moved. But unlike a cookie, a baby can take a year or more to “set”, in the meantime, it risks getting squished from handling. To ensure straight limbs and body, a freshly born baby will have its arms and legs bound straight, and then be burritoed in swaddling clothes, and in some cases attached to a board for convenient transport. The swaddling bands were believed to not only help the limbs set properly, they also help prevent the baby’s warm, moist humors from escaping.

Wrapping the infant Jesus, Psalter ms. 15, fol. IXr, France 13th century (Aix-en-Provence, Bibliothèque Municipale)

“Every part of its limbs ought to be restrained and joined in bandages, and its features ought to be straightened, that is, its head, forehead, nose. The belly and loins should be tempered, lest much of the oiliness or humidity exit from them”


This was also the rationale for discouraging old people from handling the new baby too much, as they’d unwittingly leech the heat and moisture right out of it with their cold, dry humors.  


Breastmilk was thought to be the same fluid as menstrual blood, converted by pregnancy. This explained why the menses stopped during pregnancy and breastfeeding. This was also a reason why so many high-born women (professional breeders) had someone else to breastfeed so their menstrual blood (and their fertility) could return (also, breastmilk stains silk). This was also why breastmilk was thought to be lacking in quality if the woman providing it started having her period or became pregnant.

When disease was present in the infant, instead of examining the infant itself, humoral physicians would look at the diet and lifestyle of the mother or wetnurse first. For example, foods containing “sharp humors” such as vinegar or tart fruits, were discouraged because it could cause a humoral imbalance in the baby through the milk. 

Humoral Pediatrics?

Conditions that would send a modern parent rushing into their pediatrician or ER, a medieval parent had few options within the humoral framework. In many cases, the general consensus was that nothing medical could be done for infants with serious conditions as the treatments to expel excess humors were considered too dangerous for the infant’s body. For example, bloodletting a baby with a fever? No thank you. Thomas Phaer described the situation in his 1544 book: 

“the tender babes are oftentymes desolate of rememdye, for so much as many do suppose that there is no cure to be ministered unto them by reason of their weakness”

Boke of Chyldren, Thomas Phaer

It was because of this “weakness of infancy” and the limitations of their knowledge, that the field of pediatrics was one of the last to develop in western medicine. Phaer was the first in England to write a book exclusively on pediatrics. In it, he adapts humoral principles while combining local folkways and natural magic which had been the province of women healers before physicians started taking over what were traditionally women’s roles.

The humoral theory was an understanding of the body codified by Hippocrates and Galen that persisted for at least 2000 years in Europe. The goal of humoral medicine was to prevent disease by keeping the humors in balance and/or by expelling excess humors when they built up and caused disease. Under this paradigm, women were cold men, fetuses didn’t get a soul until the quickening, and newborn babies were so warm and moist as to need bracing to avoid malformations. For newly pregnant women and sick babies, there was little that could be done to treat illnesses within the humoral framework due to their weakness and the extremity of humoral treatments., for example, bloodletting and purging. Due to these limitations, the field of paediatrics was one of the last to be developed, then only as humoral medicine was on its way out.  

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Phaer, Thomas. 1544. The Boke of Chyldren.

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