The rabbit test was a form of "
bioassay"
pregnancy test developed in the late 1920s. When a woman is pregnant she produces a hormone called
human chorionic gonadotropin. Its function is to keep the
placenta from rejecting an
embryo. Human chorionic gonadotropin also gets excreted in
urine. If the urine is then injected into a (female) rabbit and human chorionic gonadotropin is present, the rabbit's ovaries will manifest bulging masses (i.e., corpora hemorrhagica). A few days after the urine is injected, the rabbit is euthanized and dissected. The doctor examines the ovaries.
There's a popular misconception that
pregnancy via the rabbit test was determined whether the bunny lived or died. Death indicated the woman was pregnant. This is not true. In fact, since
dissection was the preferred method of ovary examination, the rabbit always died regardless if the human woman was pregnant or not. This misconception lead to "
the rabbit died" entering popular speech as a
euphemism for "she got
knocked up".
Modern pregnancy tests (like the
HPT) still look for human chorionic gonadotropin, however, they do so directly, ensuring there finally came a day no rabbits would die.
* * *
Rabbit Test is also a bad 1978 movie directed by
Joan Rivers and starring
Billy Crystal. Crystal plays a man who gets pregnant.
Roddy McDowall plays Crystal's
gynecologist. That creeps me out a little.