The "rabbit test" refers to the late 1920s method of injecting a woman's urine into a female rabbit to test for pregnancy. Within several days of doing the test, the rabbit's ovaries will show changes if the woman is pregnant. The changes occur due to the presence of human chorionic gonadotropin (hCG), which is a hormone that occurs in the uterus when a woman's egg is fertilized.
The expression "the rabbit died" was commonly used to mean that a woman was given a rabbit test and was found to be pregnant. However, although popular, the term is incorrect as the rabbit died whether the woman was discovered to be pregnant or not. The animals had to be killed in order to examine the ovaries. This test was later revised so that ovarian changes could be checked for on live, rather than dead, rabbits.
Blood tests and home pregnancy urine tests replaced the rabbit test. Both of these methods also test hCG in the body, but do not use rabbits at all. In contrast to the other methods, the rabbit test is a bioassay, or animal-based, type of test.
Dr. Maxwell E. Lapham was one of the medical researchers who worked on the development of the rabbit test. He was the director of the Division of Medical Extension and then dean emeritus at the Tulane University School of Medicine in New Orleans, Louisiana, the United States. Dr. Lapham died in 1983 at the age of 83.
The rabbit test is also known as the Friedman test after Maurice H. Friedman. Friedman, a German, was the first person to use rabbits for pregnancy tests. Friedman developed his test from the first pregnancy test, the Aschhiem-Zondek, used on mice.
The Aschhiem-Zondek pregnacy test was invented by Germans Selmar Aschheim and Bernhard Zondek. It was Zondek who first discovered the hormone hCG in pregnant women. Friedman's rabbit test was found to be more accurate than the Aschheim-Zondek pregnancy tests done with mice.