Before pregnancy tests came packaged in sterile, reliable, and user-friendly kits, many women learned they were pregnant from an African clawed frog. If you (like us) are currently scratching your head over this bizarre fact, allow us to take you back to the 1930s.
In 1938, Dr. Edward R. Elkan wrote in the British Medical Journal about a series of experiments conducted by Hogden in 1930 and 1931 that involved injecting a female African clawed frog with urine samples from human women. If the frogs in question laid eggs afterward, that meant the woman who provided her urine was pregnant. This was due to the "pregnancy hormone" in humans (human chorionic gonadotropin) kicking off ovulation in the frog.
Today, the practice sounds nearly unthinkable, but thousands of African clawed frogs were exported across the world from the 1930s all the way up to the 1950s for this very purpose. In other words, it was the first mainstream pregnancy test.
So how reliable was it? Well, one researcher reported that after conducting these pregnancy tests on 150 frogs, he never got any false positives. He did miss three actual pregnancies, though, so this method obviously wasn't quite as reliable as the modern-day pregnancy test. On top of that, they also took a lot longer than today's sticks — can you imagine the agony of waiting anywhere between five and 12 hours to learn whether you were expecting? Yikes.
That said, it's clear that these African clawed frog pregnancy tests paved the way for the future conveniences that we have today. Isn't amazing how far science has come since then?