The Rabbit Died

In the long-gone days before fifteen-minute home pregnancy tests made it obsolete, the only way a woman had to find out she was pregnant -- at least before the physiological effects made it obvious -- was the classic "rabbit test". Properly known as the "Friedman test", this involved injecting a female rabbit with a woman's urine, and then examining its ovaries a few days later to see if they had enlarged from the presence of the hormone hGC in it.

"The Rabbit Died" became a Stock Phrase for a positive -- that is, pregnant -- result. Although it was replaced in the 1960s by immunoassays that didn't involve animal testing, "the rabbit test" and "the rabbit died" remained in the popular lexicon for several decades afterward. Today in the early 21st century it is almost but not quite a Forgotten Trope, still hanging on despite all the variations on the different ways various home pregnancy tests announce their results have tried to displace it over the years. It can still be heard now and then, though, usually in a humorous context, as well as in period works, of course.

Not to be confused with Doctor Rabbit or anything involving Bugs Bunny.

Fan Works
"Calypso sighed, "Your mum mentioned that if it had been more than a week since Harry and I..." she paused, blushing, and Buffy grinned. "Well, anyway, she said that if it had been more than a week, we could go to Madame Pomfrey and she could tell if we'd... er..." "Killed the rabbit?" Harry and Calypso both gave her confused looks. "What?" Harry asked. Buffy rolled her eyes. "Geez, you guys are SO out of the loop that the loop doesn't know you exist, I swear. I don't even really know where the saying came from, but I think it has something to do with a really, REALLY old way of figuring out if a girl is pregnant. It's just a cliché. Sorry, go on.""
 * In chapter 26 of Fool's Consequences, a Harry Potter/Buffy the Vampire Slayer fanfic by "EllandrahSylver", Buffy invokes and discusses the trope:

Film

 * Alluded to in Grease 2 during the song "Reproduction", when one of the T-Birds holds up a white rabbit and says, "See what happens when a boy and girl don't know how to play it safe?"
 * Provides the title for the 1979 Billy Crystal film Rabbit Test about a man getting pregnant.
 * Similarly, the 2016 Short Film The Rabbit Died is about a man getting pregnant.

Live-Action TV

 * In "What's Up, Doc?", a sixth-season episode of M*A*S*H, the only way for Margaret to find out if she's pregnant is to use one of Radar's rabbits for a rabbit test.
 * Invoked in the episode "The Coat Hanger" of American Horror Story when Sister Mary Eunice says "The bad news is, the rabbit died" to Lana.

Music
"You're telling her things but your girlfriend lied You can't catch me 'cause the rabbit done died ''Yes it did"
 * Invoked in "Sweet Emotion" by Aerosmith: