By Dave Mosher

Note: Mosher visited the National Xenopus Resource at the Marine Biological Laboratory in June; his recaps his visit in the article below.

Pregnancy tests today are as simple as peeing on a toothbrush-size stick and waiting a few minutes. Chemicals in the sticks can detect a key pregnancy hormone: human chorionic gonadotropin (hCG).

Back in 1920s and 30s, however, the best available test for hCG was much slower, less accurate — and pretty gruesome.

Called the Aschheim-Zondek or “A-Z” test, it required injecting several female mice, rats, or rabbits with a woman’s urine, waiting a few days, killing the rodents, and then examining their ovaries for any enlargement spurred by the hormone. By 1935, an English lab was performing 6,000 A-Z tests a year.

But a new pregnancy test was actively being discovered at the same time, and it wound up reigning for more than two decades. ….

“You used take a woman’s urine, inject it into the back of the frog, and if the frog laid eggs 12 hours to 24 hours later, you knew the woman was pregnant,” Marko Horb, who directs the NIH-funded National Xenopus Resource in Woods Hole, Massachusetts, told Business Insider. Read more …