Speaker 1: Welcome to brain Stuff, a production of I Heart Radio.
Speaker 1: Hey brain Stuff, Lauren Volga Baum Here. When they're in
Speaker 1: our human world, rabbits can be interesting pets, a source
Speaker 1: of food assistance in classic magicians, stage shows, or animal models,
Speaker 1: and laboratory tests. Of course, we hope that in all
Speaker 1: of these cases, the rabbits in question are being treated
Speaker 1: by the humans in question with the utmost care. But
Speaker 1: did you know that from the nineteen thirties to the
Speaker 1: early nineteen sixties, lab rabbits were key element in human
Speaker 1: pregnancy tests. It's true, and it's even weirder than it sounds,
Speaker 1: because it involved injecting those rabbits with human urine. But
Speaker 1: let's back up a little here. The basic principles behind
Speaker 1: testing urine for pregnancy date back thousands of years and
Speaker 1: continue to this day. Historians believe the physicians of ancient
Speaker 1: Egypt were the first to discover a method detecting pregnancy
Speaker 1: through the study of urine. We've talked about this one
Speaker 1: on the show before. By BC or so, ancient Egyptian
Speaker 1: women could determine whether they were pregnant by urinating in
Speaker 1: two different bags, one filled with barley and the other
Speaker 1: with wheat. If the grain and either bags sprouted, it
Speaker 1: meant she was expecting fast forward all the way. In
Speaker 1: the nineteen sixties, a study found that this is actually
Speaker 1: accurate about seventy percent of the time because the elevated
Speaker 1: estrogen levels and a pregnant person's urine can promote seed growth.
Speaker 1: What wasn't accurate was the attempt to determine the sex
Speaker 1: of the child based on which sprouted first, Barley for boys,
Speaker 1: wheat for girls. But still not bad and historians think
Speaker 1: this marked the beginning of medical urine examination and potentially
Speaker 1: laboratory medicine itself. More than three thousand years of urine
Speaker 1: examination also called eurro scopy or your analysis have followed,
Speaker 1: with varying accuracy. There was a bit of an expose
Speaker 1: in the sixty hundreds in London that called out fraudulent
Speaker 1: physicians using urine to diagnose pregnancy and lots of other conditions.
Speaker 1: The whistleblower referred to these frauds as piss profits. But
Speaker 1: urine research continued, and meanwhile, in the late eighteen nineties,
Speaker 1: scientists discovered the existence of hormones. A hormone is a
Speaker 1: product that sells make to regulate specific cellular activities such
Speaker 1: as cell growth and division, and in the nineteen twenties,
Speaker 1: scientists pinpointed a specific hormone called human choreonic ganado trop in.
Speaker 1: It's also called hCG because that's much easier to say.
Speaker 1: This hormone is found almost exclusively in the blood and
Speaker 1: urine of pregnant people, though we now know that certain
Speaker 1: cancers also produce it in anyone. But intrigued by this
Speaker 1: hormones linked to pregnancy, a couple of German researchers set
Speaker 1: out to develop a method of testing for hCG in urine.
Speaker 1: They decide to exploit the fact that hormones from one
Speaker 1: animal can generate biological responses in the bodies of other species,
Speaker 1: sort of like those sprouting seeds. They discovered that by
Speaker 1: injecting female mice with a pregnant woman's urine, they could
Speaker 1: stimulate the mice's ovaries and cause them to go into
Speaker 1: heat within a few days. They called this test the
Speaker 1: A Z test. Will note here that just as analyzing
Speaker 1: urine has a long history and medical science, so too
Speaker 1: has the use of animals. While often controversial and hopefully
Speaker 1: replaceable by technology in the future. A number of experiments
Speaker 1: on animals called bioassays, have led to important breakthroughs in
Speaker 1: medical science anyway, during the nineteen thirties, researchers applied the
Speaker 1: Azy tests methodology to two other species. In South Africa,
Speaker 1: researchers adapted it for use in frogs, inventing the hogbin test.
Speaker 1: The frogs would lay eggs if the urine they were
Speaker 1: injected with contained hCG. This test was used tens of
Speaker 1: thousands of times in the nineteen forties through the nineteen sixties,
Speaker 1: and at the University of Pennsylvania Medical School, one Dr
Speaker 1: Maurice Friedman made a breakthrough with rabbits similar to mice,
Speaker 1: If hCG is present in urine injected into female rabbits,
Speaker 1: the urine stimulates changes to the rabbit's ovaries within just
Speaker 1: a few days. The hCG basically fools the rabbit's body
Speaker 1: into temporarily thinking it's pregnant, and the rabbit's ovaries produced
Speaker 1: temporary tissue structures that a researcher can spot. The urine
Speaker 1: injection itself didn't harm the rabbit or the mice or frogs,
Speaker 1: but unfortunately, the fastest way to check the ovaries of
Speaker 1: the mammals was to euthanize and dissect the animal. Thousands
Speaker 1: of rabbits were sacrificed every year, to the point that
Speaker 1: the rabbit died became a euphemism for saying that someone
Speaker 1: was pregnant. The frogs, however, were unharmed and uh reusable.
Speaker 1: Luckily for the bunnies, though, The first immuno essay that
Speaker 1: could test directly for hCG and a sample of urine
Speaker 1: was developed in nineteen sixty. Immuno essays are tests that
Speaker 1: use specific molecules called antibodies that can bind onto whatever
Speaker 1: type of particle you're looking for in some detectable way.
Speaker 1: Maybe it makes the sample clump up, or maybe the
Speaker 1: antibody is attached to an enzyme that will change the
Speaker 1: color of a test strip from white to blue. And yes,
Speaker 1: today's at home COVID tests are also immuno essays. But
Speaker 1: it took over a decade to turn this initial discovery
Speaker 1: into something really usable for pregnancy testing. It involved a
Speaker 1: lot of research and societal changes, including advancements in prenatal
Speaker 1: care and the legalization of most abortions at a national
Speaker 1: level via the Supreme Court's decision in Roe v. Wade
Speaker 1: in ninety three, both of which incentivized being able to
Speaker 1: detect pregnancy as soon as possible. At that time, the
Speaker 1: best tests available had be sent away to a lab,
Speaker 1: and we're only reliable for detecting pregnancy at six weeks
Speaker 1: or later. The first home pregnancy test that's more or
Speaker 1: less equivalent to the ones we know today was approved
Speaker 1: for home use in nineteen seventy six and was on
Speaker 1: store shelves by early night. With the sample of urine,
Speaker 1: it could display a result within two hours, though it
Speaker 1: wasn't as accurate as early as today's tests are. A
Speaker 1: Modern pregnancy tests still involved detecting hc G, but have
Speaker 1: gotten more sensitive, meaning they can detect smaller amounts of
Speaker 1: it sooner in a pregnancy. Okay, a person's body starts
Speaker 1: producing hCG when a fertilized egg implants itself, hopefully in
Speaker 1: the prepared lining of the uterus. See our previous episode
Speaker 1: on how human conception works for more on that, but basically,
Speaker 1: under normal circumstances, a person will ovulate about a week
Speaker 1: after their last period, and if that ovulated egg is fertilized,
Speaker 1: it'll implant about a week after that. A so that's
Speaker 1: two weeks into a pregnancy, because pregnancies are calculated from
Speaker 1: the end of a person's last period, and that's when
Speaker 1: the pregnant body starts producing hCG. The presence and or
Speaker 1: levels of hCG in a person's body can be detected
Speaker 1: in two ways, via blood test or via urine test.
Speaker 1: A blood test is a little more accurate, but also
Speaker 1: more invasive. You have to get blood drawn and often
Speaker 1: more expensive. You have to go to a medical care
Speaker 1: provider to get your blood drawn and send the sample
Speaker 1: to a lab. But a blood test can detect the
Speaker 1: presence or quantity of hCG in your blood as early
Speaker 1: as two to three weeks into a pregnancy, and so
Speaker 1: before you would have ever missed your period, though it
Speaker 1: can take a day or more to get the lab
Speaker 1: results back. A urine test is more common because even
Speaker 1: though it's a little less accurate, especially early in a pregnancy,
Speaker 1: it's cheaper, can be done anywhere, and the results are
Speaker 1: pretty much immediate. These are done by either collecting a
Speaker 1: sample of urine and dipping a testing strip into the sample,
Speaker 1: or by urinating directly on a testing strip. A urine
Speaker 1: test can generally detect the presence of hCG three to
Speaker 1: four weeks into a pregnancy, so from slightly before to
Speaker 1: right after you would have missed your period, and the
Speaker 1: results develop on the strip within a few minutes. These
Speaker 1: tests do very a little, so if you're taking one,
Speaker 1: just read and follow the instructions, but rest assured that
Speaker 1: there will be no rabbits, frogs, or barley involved. Today's
Speaker 1: episode is based on the article how can a Rabbit
Speaker 1: Tell Me If I'm pregnant? On how stuff works dot
Speaker 1: com written by Robert Lamb. Brain Stuff It's production of
Speaker 1: I Heart Radio in partnership with how stuff works dot Com,
Speaker 1: and it's produced by Tyler Klang. Four more podcasts from
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