In A Nutshell
In the years prior to the ubiquitous plastic sticks we use today, pregnancy was determined by injecting a woman’s urine into mice and rabbits, which were then dissected to see the results. Frogs were used later: They would go into ovulation within hours if the result was positive. The frog test was the world standard until the 1970s.
The Whole Bushel
Today’s pregnancy tests are mostly foolproof and incredibly accurate, but those administered in olden times were far more dubious. The link between urine and pregnancy was understood as long ago as ancient Egyptian times; they would pour the woman’s urine over wheat and barley grains. If it germinated, that meant she was pregnant. Whether the wheat or barley sprouted would indicate the sex of the fetus. Obviously, this methodology was flawed on many levels. The technology did not improve significantly during the Middle Ages: Most tests during this era were outright quackery.
After the link between pregnancy and hormones was established at the beginning of the 20th century, the A-Z test was invented by chemist Selmar Aschheim and gynecologist Bernhard Zondek in the late 1920s. It was a rather cruel trial—five female mice were injected with the urine of a prospectively pregnant woman over the course of a few days, then dissected. If their ovaries were swollen, it would indicate that the woman was pregnant. Later, rabbits would be used.
Shortly thereafter, British zoologist Lancelot Hogben pioneered the frog pregnancy test while conducting research at the University of Cape Town in South Africa. The Hogben Test involved injecting the woman’s urine into the African clawed frog. If the woman was pregnant, the frog would ovulate in a matter of hours. Most importantly, the frogs could be re-used and would not have to die to complete the test. Though it sounds terribly archaic today, the Hogben frog test was the world standard in pregnancy testing for decades. The African clawed frog would go on to have a lasting legacy in animal testing, becoming the first vertebrate species ever cloned.
Unfortunately, the African clawed frog is also the the carrier of a deadly fungus called Batrachochytrium dendrobatidis, which infects the skin of amphibians and causes them to die within weeks. The clawed frog has evolved so that it is unaffected by the fungus, but the disease has now become a major threat to hundreds of other amphibian species that have not built up an immunity.