Rabbit test

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 woman in the early months of pregnancy is injected into immature female mice, the ovaries of the mice enlarge and show follicular maturation. 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 secreted only 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.