The rabbit test, or "Friedman test", was an early pregnancy test developed in 1931 by Maurice Harold Friedman and Maxwell Edward Lapham at the University of Pennsylvania as an improvement on the 1927 test developed by Bernhard Zondek and Selmar Aschheim. The original test actually used mice, and was based upon the observation that when urine from a female in the early months of pregnancy is injected into immature female mice, the ovaries of the mice enlarge and show follicularmaturation. The test was considered reliable, with an error rate of less than 2%. The rabbit test consisted of injecting the tested woman's urine into a female rabbit, then examining the rabbit's ovaries a few days later, which would change in response to a hormone only secreted by pregnant women. The hormone, human chorionic gonadotropin (hCG), is produced during pregnancy and indicates the presence of a fertilized egg; it can be found in a pregnant woman's urine and blood. The rabbit test became a widely used bioassay (animal-based test) to test for pregnancy. The term "rabbit test" was first recorded in 1949 but became a common phrase in the English language.
Modern pregnancy tests still operate on the basis of testing for the presence of the hormone hCG. Due to medical advances, use of a live animal is no longer required.
It is a common misconception that the injected rabbit would die only if the woman was pregnant. This led to the phrase "the rabbit died" being used as a euphemism for a positive pregnancy test. In fact, all rabbits used for the test died, because they had to be surgically opened in order to examine the ovaries. While it was possible to do this without killing the rabbit, it was generally deemed not worth the trouble and expense.
A replacement for the rabbit test involved using frogs, specifically the African clawed frog, which like all frogs lays eggs instead of getting pregnant, and therefore can yield a positive result on the test without the need to be cut open in order to prove it.
In popular culture
In Neil Gaiman's Sandman issue 31 Hazel worries that a pregnancy test means she will have to kill a rabbit since she is a vegetarian before Barbie tells her the rabbit test was from the olden days.
In "Maude's Dilemma Part 1", a season 1 episode of "Maude", Maude tells her husband "the rabbit died," in reference to her positive pregnancy test.
In "Hands and Knees," a Season 4 episode of Mad Men, Roger Sterling asks Joan Harris, "Did you take a rabbit test?" when she reveals to him her suspicions she is pregnant with his child.
An independent short film titled Redemption Maddie centers on the idea of testing pregnancy with rabbits.
In the seventh episode of the second season of The Dick Van Dyke Show, Mary Tyler Moore's character Laura says "the rabbit died" to convey the news to Rob that she is pregnant.
In "The Stomach Mumps" (S 6, Ep 6), of the sitcom Good Times (first aired Oct. 14, 1978) Willona shields Penny from the facts of life. "Yesterday she's asking about Peter Rabbit and today she's asking about the rabbit test."
A collection of essays by Teresa Bloomingdale, columnist and mother of ten, bears the title I Should Have Seen It Coming When the Rabbit Died (1979). The title refers to an anecdote (1956) in which the rabbit used in her first pregnancy test died from jumping off the examination table, thereby shrugging off any responsibility for her ever-growing family.[clarification needed]
In the M*A*S*H episode, "What's Up, Doc" (S6, Ep19), Hawkeye removed the ovaries from Radar's rabbit "Fluffy" to run the test when Maj. Margaret Houlihan suspected she was pregnant.
In the Showtime dramedy Californication, two of the main characters (Hank and Marcy) each use the phrase "the rabbit done died" in separate episodes when they are not pleased with a positive pregnancy test.
In the Squidbillies episode "Family Trouble",first aired November 13, 2005, the rabbit test is referenced in a paternity suit.
In the television show House (Season 5, Episode 8), the character House mentions the rabbit test saying "[since a] pregnancy test only takes 5 minutes and we no longer kill rabbits [...] do the test."
In the song "Sweet Emotion" by Aerosmith the lyrics include the line "You can't catch me cause the rabbit done died."
In the 1996 film Grace of My Heart starring Illeana Douglas, her character tells her boyfriend she "is just waiting to see if the rabbit dies" while discussing her possible pregnancy.
In the 1987 film Fatal Attraction, the character Alex Forrest (Glenn Close) boils the pet rabbit belonging to the daughter of the man with whom she is having an affair (played by Michael Douglas) to communicate symbolically that she is pregnant.
In American Horror Story: Asylum, Season 2, episode 8, set in a mental institution in 1964, Sister Mary Eunice tells Lana Winters that "your rabbit died" meaning that she was impregnated by her rapist.