The second floor of the Science Museum in London, England, is dedicated to medicine and the innovations that made it possible to prevent and treat many diseases.
On a small shelf that deals with pregnancy, it is possible to see a piece that, at first, seems to have nothing to do with the theme: a frog preserved in a glass jar.
The explanation for this object being there could not be more curious: until the 1970s, when modern pregnancy tests appeared, the kind that can be bought at the pharmacy and made at home, the main method to find out if a woman was expecting a child ( or not) was to inject her urine into a toad or frog. If the amphibian released eggs right away, it meant an ongoing pregnancy.
As much as this procedure sounds like quackery, the truth is that it was the main method available for discovering a pregnancy for many decades of the 20th century, with a good enough rate of effectiveness.
And this is not the only unconventional example of techniques to determine the development of a baby in the mother’s womb. Throughout history, there are several episodes in which other animals and even grains of wheat and barley were used for this purpose. Interestingly, many of them worked reasonably.
But to understand this story from the beginning, you have to travel 3,000 years in time.
The answer lies in the grains
According to an article published in 2014 by endocrinologist Glenn Braunstein of Cedars-Sinai Medical Center in the United States, the first known records of the search for a method to detect pregnancy date back to 1350 BC and come from a medical treatise written in the United States. Ancient Egypt.
In the document, the recommendation is to mix the urine of the woman suspected of being pregnant with barley and wheat grains. If they sprout after some time, it means that she is really expecting a child.
The Egyptians also believe that if only the barley sprouted, it indicated that the baby was male. If only wheat grew, it was a girl.
Although this second part is just a hoax, the relationship between the pregnant woman’s pee and the fact that the grains sprout makes sense — pregnancy hormones can trigger the plant’s development.
In a text on the subject, the National Institutes of Health (NIH) of the United States report that, in 1963, a group of scientists decided to test whether this theory in vogue in Ancient Egypt had any basis in truth.
“They found that 70% of the time, urine from pregnant women actually promoted seed growth, whereas liquid from pregnant women didn’t have that same effect.”
The Pee Prophets
During the Middle Ages in Europe, the idea spread that it was possible to analyze a person’s state of health through bodily fluids.
As equipment such as the microscope did not exist, specialists at the time had to resort to the five senses to carry out this type of study.
Thus emerged the so-called “pee prophets”, men and women who theoretically had the training and ability to analyze the color, smell, texture and other aspects of this material.
The NIH highlights a text published in 1552, in which the urine of a pregnant woman was described as “light in color of a pale lemon, slanting towards whitish, with a cloudy appearance on the surface”.
Some of these individuals went a step further and poured wine into their urine to find out that a baby was coming. “In fact, alcohol can react with some proteins in the urine, which allowed for a moderate success rate. [nesse tipo de análise]”, inform the NIH.
Over the centuries and the arrival of the Enlightenment, however, these empirical and non-standard methods were gradually abandoned — not least because the most reliable way to confirm a pregnancy at the time continued to be observing changes in the body (such as nausea and vomiting). vomiting or the growth of the belly itself).
The hormonal discovery
From the 18th and 19th centuries, technological and scientific advances allowed us to observe what actually happens inside the human organism.
At the beginning of the 20th century, the English physiologist Ernest Starling was a pioneer in identifying and naming the body’s “chemical messengers” as “hormones”.
Although there are many substances that fit this definition, the most important of them when we talk about pregnancy is human chorionic gonadotropin, also known by the acronym hCG, identified by several groups of scientists from the 1920s.
“The basic function of hCG is to support pregnancy, especially during the first months”, summarizes the doctor Ilza Maria Urbano Monteiro, vice president of the National Commission Specialized in Contraception of the Brazilian Federation of Gynecology and Obstetrics Associations (Febrasgo).
The egg and sperm are found in the fallopian tube, in the upper part of the female reproductive system. After fertilization, this embryo needs to travel to the uterus, a little further down, where it will settle and start development for the next nine months.
It is precisely hCG that creates all the conditions for the embryo to thrive in these first stages of formation.
But is there a way to properly measure the presence of this typical pregnancy hormone?
left for the animals
The first pregnancy tests of the 20th century were developed in 1927 from the work of German scientists Selmar Aschheim and Bernhard Zondek.
In experiments, they observed that injecting the urine of a pregnant woman into a rat or mouse that has not yet reached sexual maturity stimulates the development of the ovary and the release of eggs in the rodents. The same effect did not happen if the pee of a person who was not expecting a baby was applied.
The main difference was precisely in the presence of the hCG hormone, which only appears during the nine months of pregnancy.
Thus, the AZ test was born, which refers to the surname of the two German scientists. The method, however, lacked practicality: it was necessary to inject the woman’s urine into at least five rats and wait about a week to obtain the results, according to an article signed by researcher Kelsey Tyssowski, from Harvard University, in the USA.
Years later, some specialists began to use rabbits for this type of examination, which facilitated the visualization of the ovary (due to the larger size of this species), but it came up against another inconvenience: it was still necessary to sacrifice the animal to obtain the result.
In short, this type of test was difficult, expensive, and only identified higher levels of hCG weeks after a woman was late. Therefore, he was relegated to a few laboratories and to very specific cases.
And this is how toads and frogs enter the story: these amphibians release their eggs in the wild. In other words: there is no need to sacrifice and dissect the animal to discover the result.
They then began to be used as the main proof of pregnancy: the urine of the woman who suspected she was pregnant was injected into these animals and, if it really was, the hCG hormone stimulated the release of toads and frogs’ eggs.
Between the 1940s and 1960s, the demand for amphibians for pregnancy tests generated an international trade with repercussions on the environment to this day.
An article published in the journal Nature in 2013 revealed that the importation of frogs of the species xenopus laevis from Africa to the United States brought to North America a type of fungus that causes serious disease and threatens the very existence of some local amphibian species.
The use of these animals for pregnancy tests became obsolete in the 1970s, and many clinics and hospitals released their “stocks” of frogs into the wild without any care.
Technique was also used in Brazil
Fleury Medicina e Saúde, which has a private network of diagnostic laboratories with more than 90 years of history, also offered toad and frog pregnancy tests.
The technique used in the country, however, was slightly different. It was developed by Argentine physician Carlos Galli Mainini and focused on male frogs. The proposal was to inject the woman’s urine and see if they expelled sperm for the next three hours.
“The frogs came from the Guarapiranga dam, in São Paulo, and traveled by tram to reach the laboratory”, informs the company, in a text sent to BBC News Brasil.
“The obsolescence of this technique put an end to yet another profession: that of frog hunter”, adds the note.
With 60 years of experience, the doctor Jorge Gennari remembers that he came to see pregnancy tests that used amphibians at the beginning of his career.
“I got to the very end of that era, but they were very complicated methods that, not infrequently, gave false negative results”, recalls the gynecologist and obstetrician at Hospital e Maternidade Santa Joana, in São Paulo.
“At the time, it was very difficult to detect a pregnancy early and we associated the test results with clinical exams, carried out in the office, which involved palpation of the uterus and the analysis of other changes in the woman’s body”, he adds.
A ‘private revolution’
Starting in the 1970s, the first home pregnancy tests arrived on the market in Canada and the United States.
The initial version, which was developed by American publicist Margaret Crane, looked like a chemistry kit: it came with test tubes, different vials of products and required the woman to follow a series of steps to ensure a reliable result.
The test was advertised in magazine pages as a “private revolution”, for the convenience of being able to discover or rule out a pregnancy in the comfort of home, without needing the help of a doctor.
What did not change was the material used —urine— and what was sought to be identified: the hCG hormone.
From the late 1980s onwards, tests more similar to the current ones appeared, which bring a rod with a visor, in which the appearance of bands or other symbols of a certain color determines the pregnancy (or not).
It is curious to note that, since Ancient Egypt, urine has always been the subject of many of these tests. The modern explanation for this is that hCG, produced by the placenta, enters the mother’s bloodstream, ends up being filtered by the kidneys and discarded through the pee.
But it is worth remembering that there are also options in several clinical analysis laboratories to measure this hormone directly in the blood.
The advancement of the last few decades in this area has been so rapid that the waiting time for the result of such a test has gone from weeks, or even months, to a few days, hours or minutes.
“In some cases, it is possible to know about a pregnancy when there is a menstrual delay of a few days”, calculates the gynecologist and obstetrician Marco Antonio Lopes, from Fleury Medicina e Saúde.
Monteiro, from Febrasgo, highlights that the availability of such accessible and reliable methods represents more security for the woman and the baby in formation.
“In Brazil, 52% of pregnancies are unplanned. The sooner the pregnancy is detected, the better the monitoring, in addition to being possible to suspend the eventual use of drugs that could affect the development of the fetus in these early stages”, he argues.
Gennari draws attention to another recent evolution in this area of medicine: imaging tests. “Associated with blood and urine analysis methods, today we have very modern ultrasound devices, capable of identifying changes in the early stages of embryo development.”
Finally, Lopes points out that there is room for more innovation and the future promises an even more complete and safer early follow-up for future mothers and their children.
“We are increasingly focused on genetics, which allows us to make an early diagnosis of problems that may appear at the end of pregnancy”, he points out.
“The analysis of genes will also allow us to discover things at an earlier age that are clinically important for the individual for the rest of his life”, concludes the gynecologist.
