Which frog was widely used in the Hogben pregnancy test?

The frog widely used in the Hogben pregnancy test was the African clawed frog, Xenopus laevis.

In the 1930s, researchers discovered that injecting urine from a pregnant woman into a female X. laevis could trigger ovulation within roughly 8–12 hours. The response occurred because the urine contained human chorionic gonadotropin (hCG), a hormone associated with pregnancy. Eggs released by the frog provided the visible positive result.

The method was faster and more humane than earlier mouse and rabbit tests, which often required several days and the animal’s death for examination. The frogs could generally be reused, helping make the test practical and widely available from the 1930s through the 1960s.

A common mix-up is with the Galli-Mainini test, which used male frogs or toads and detected sperm release instead. The Hogben test is also tied to a scientific-credit dispute: Lancelot Hogben popularized the method, while South African researchers Hillel Shapiro and Harry Zwarenstein published important early pregnancy-testing work with Xenopus. Modern immunological tests eventually replaced the frog method.