Fracts #2 – A frog can tell you’re pregnant?

Before the modern development of pregnancy test kits, what is one of the ways that can tell you’re pregnant?

You guessed it…


For 20 years, 1930s to 1950s, Scientists around the world had been using South African Clawed Frogs for research as well as conducting pregnancy test.

Wait a second, how do you use frog to test for a baby?

Once urine sample is collected, it is then injected into the frog’s dorsal lymph sac in the morning and by the end of the day, results can be concluded. A dose of a pregnant woman’s pee will cause a female South African Clawed Frog to lay effs within eight to 12 hours. The test also works on male frogs, which produce sperm in response to the injection.

Why does it work?

It works because a pregnant woman’s urine contains a hormone called human chorionic gonadotropin, or hCG. This is exactly how most modern pregnancy test rely on the detection of hCG using other means like antibodies after 1960s.

In 1930, a scientist based in Cape Town, South Africa, named Lancelot Hogben reported that he could use ox hormones to control ovulation in a local frog species—Xenopus laevis. His discovery was important for two reasons: First, it provided embryologists with a frog that could produce eggs year-round. Second, it provided doctors with a new animal for pregnancy testing. By 1933, doctors were using the “Hogben test” to detect hCG in urine.

The Hogben test was both rapid and reliable, and it spread quickly throughout Europe and the United States over the next two decades. Scientists were able to rear the clawed frogs in captivity, but it was easier to import them from Africa in large numbers. Either way, the reliance on live animals posed problems for the big testing centers. Even a facility with several thousand frogs could be shut down by a virulent disease outbreak. The development of new testing methods in the 1960s made the Hogben test obsolete.

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