Mythbuster: The Day “The Rabbit Died”
Nope, this is not a new rendition of “Bye-bye, miss American pie” by Don McLean. “The Rabbit Died” used to be a common phrase referring to a positive pregnancy test and originates from the first tests that were developed in the 1920s. The initial pregnancy tests involved injecting a woman’s urine into a female rabbit-strange but true!
If the woman were pregnant, her urine would contain trace amounts of the hormone, human chorionic gonadotropin (but most people call it hCG). Interestingly, hCG in the urine of a woman can also affect female rabbits. In response to hCG, the ovaries of a rabbit respond by swelling in size and turning a bright yellow color, essentially what happens to the woman’s own ovaries. To investigate the rabbit’s ovaries, scientists originally had to kill all of rabbits that were injected with urine. As such, the rabbit died whether or not a woman was pregnant. So, literally, the day the rabbit died, would have had absolutely no relevance to pregnancy.
Rabbits were not the only animals sacrificed during these early tests. Mice and frogs were also used. During later renditions of the test, clinicians learned how to investigate ovaries without killing the animals at all. While we no longer have to rely on animals to determine pregnancy, modern day tests still measure the hCG in urine.
It is not understood how this fallacy became part of the American lexicon but a large number of television shows and movies make allusions to rabbits and pregnancy. In 1978, a young Billy Crystal even played a pregnant man in the movie “Rabbit Test.” More recently, an episode of House also made an obscure reference to the rabbit test in pregnancy. Tell us if you see other allusions to the rabbit test in movies and television!