Why, when, and how did they use rabbits for pregnancy tests?

Mattaboy!

My wife and I found out recently that she is pregnant, which brought to mind that old phrase, "The rabbit done died." This got me thinking about that wacky scientific/medical practice of using rabbits as a pregnancy test, and now I need some answers. What exactly did they do to the rabbit? Who came up with this? When? How? Why rabbits? Help me out, Matt.

-- P, the net

He done died, eh. Well, I done found out what killed him. Her, actually. Wacky or not, the rabbit test was the first reliable medical pregnancy test, aside from waiting nine months. It was developed by a researcher in physiology at the University of Pennsylvania in the 1930s. Urine from a woman who suspected she was pregnant was injected into a female rabbit. Pregnant-lady urine contains a lot of chorionic gonadotrophin. If the woman was pregnant, the hormone jolt would cause the rabbit's ovaries to enlarge and develop characteristic surface changes. Unfortunately, the only way to read the test results was to open up bunny and look around. So it wasn't so much that the rabbit done died; more like the rabbit was done in. Hold on a moment while I envision a shelf full of 1950s-era home pregnancy tests. Lots of wiggling noses and a big knife.