Once Upon a Time, Frogs Were Pregnancy Test Kits

Even in the 1960s, samples would be injected into live amphibians

Photo: Pexels

All over the world, pregnancy tests are an emotionally charged event. Few other results can swing people across excitement, anxiety, astonishment, or paranoia, all just in a matter of seconds. Irrespective of why someone’s taking the test, the magnitude of the result can be extremely unsettling. The tests would have been so much more daunting, had they entailed injecting urine samples in a frog and patiently waiting for it to lay eggs like they used to not so long ago. Even though today it sounds borderline insane, this is exactly how pregnancy tests were conducted through a major chunk of the previous century. Unlike a lot of discontinued medical practices, frog tests were no quackery, in fact, they were almost impeccably accurate. Through the 1950s, women would deposit samples at nearby clinics which were then dispatched to laboratories for processing. Decades before Paul the Octopus had parted his eyelids, African clawed frogs were dishing out pregnancy predictions.

The unusual method was discovered by a British scientist, Lancelot Hogben while working on hormones. In 1927, he moved to South Africa and began studying the impact of hormones on indigenous amphibians. During one such experiment, he encountered the fortune-teller-to-be, Xenopus Laevis. Owing to the tamability of the frog, he slowly incorporated the organism as his go-to lab rat. In 1930, Hogben injected an extract from an ox’s pituitary gland into the animal and noticed that it had started laying eggs. Researchers back then were aware of the presence of pituitary hormones in pregnant women and that they were related to the development of ovaries. The erstwhile pregnancy tests would inject these hormones into rodents and ascertain pregnancy by gauging the development of their ovaries. Hogben instantly identified the potential of his discovery and began taking measures to establish frogs as a viable alternative to the existing methods.

In 1937, Hogben imported around 1500 Xenopus frogs to the UK and began raising them in laboratories. When doctors would request a ‘Hogben test’, a living frog would be injected with the sample. If the woman was pregnant, the presence of chorionic gonadotropin in the urine would kick off ovulation in the frog. The results were extremely precise and articles in the British Medical Journal hailed the efficacy of the test. In most cases, the frog would lay eggs within the next 24 hours, greatly reducing the longer time frame mandated by the previous tests. The cost of raising frogs was much smaller than that of maintaining rodents, skewing the researchers towards the Hogben Test. Moreover, with a lifespan of around thirty years, the African clawed frogs could be used multiple times. The larger scientific community saw this as a much more humane method compared to vivisecting rodents. As the method gained traction, thousands of frogs were transported around the world as living pregnancy kits.

However, the use of the frogs did not completely change how we approached pregnancy. For starters, women couldn’t individually apply for the test and had to put in a request via their GP. In most cases, the doctors would prefer to rely on physical signs of pregnancy than automatically ask for the Hogben Test. Despite the restricted use of the method, thousands of frogs became harbingers of the good news to various families. In the 1960s, parenthood saw another great revolution with the development of cell-based pregnancy tests. Coinciding with the feminist upsurge and the sexual revolution of the 60s, this invention placed more autonomy in the hand of expecting parents. As the Hogben Tests were phased out, the Xenopus frogs found a new role in medical laboratories. Decades of working with the amphibians had convinced researchers about the governability of the frogs. Long after their use as pregnancy kits, the frogs were deployed in a whole range of experiments including toxicology and electrophysiology.

In recent years, scientists have registered an alarming phenomenon. The global amphibian population seems to be on a fast decline due to the rapid spread of chytrid, a pathogenic fungus. The latest research connects the rampant export of African clawed frogs to the proliferation of the infection. It is widely believed that chytrid coexisted with Xenopus frogs in their native environment but their introduction into different ecosystems has led to detrimental consequences. Looking at the comfort of modern-day pregnancy tests, it is hard to believe that all this started from a bunch of lab frogs. It’s extremely intriguing to study how a single scientific discovery can revolutionize so much and still lead to such unforeseeable yet turbulent shifts in nature. The history of frogs as pregnancy kits bears testament to how there’s so much we don't know and we better be cognizant of our ignorance lest we accidentally perturb some dangerous trip-wires.

More by Shourya Agarwal

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