WEBVTT - How Were Pregnancy Tests Invented? 0:00:01.920 --> 0:00:04.280 Welcome to brain Stuff, a production of I Heart Radio. 0:00:06.600 --> 0:00:10.680 Hey brain Stuff, Lauren Volga Baum Here. When they're in 0:00:10.840 --> 0:00:15.000 our human world, rabbits can be interesting pets, a source 0:00:15.040 --> 0:00:19.480 of food assistance in classic magicians, stage shows, or animal models, 0:00:19.480 --> 0:00:22.759 and laboratory tests. Of course, we hope that in all 0:00:22.760 --> 0:00:25.680 of these cases, the rabbits in question are being treated 0:00:25.720 --> 0:00:28.880 by the humans in question with the utmost care. But 0:00:29.160 --> 0:00:31.720 did you know that from the nineteen thirties to the 0:00:31.720 --> 0:00:36.720 early nineteen sixties, lab rabbits were key element in human 0:00:36.800 --> 0:00:41.519 pregnancy tests. It's true, and it's even weirder than it sounds, 0:00:41.720 --> 0:00:45.479 because it involved injecting those rabbits with human urine. But 0:00:45.880 --> 0:00:49.160 let's back up a little here. The basic principles behind 0:00:49.280 --> 0:00:53.000 testing urine for pregnancy date back thousands of years and 0:00:53.080 --> 0:00:57.880 continue to this day. Historians believe the physicians of ancient 0:00:57.920 --> 0:01:01.000 Egypt were the first to discover a method detecting pregnancy 0:01:01.120 --> 0:01:03.720 through the study of urine. We've talked about this one 0:01:03.720 --> 0:01:08.160 on the show before. By BC or so, ancient Egyptian 0:01:08.200 --> 0:01:11.080 women could determine whether they were pregnant by urinating in 0:01:11.160 --> 0:01:14.760 two different bags, one filled with barley and the other 0:01:14.880 --> 0:01:18.360 with wheat. If the grain and either bags sprouted, it 0:01:18.520 --> 0:01:22.080 meant she was expecting fast forward all the way. In 0:01:22.120 --> 0:01:24.600 the nineteen sixties, a study found that this is actually 0:01:24.640 --> 0:01:28.040 accurate about seventy percent of the time because the elevated 0:01:28.160 --> 0:01:31.560 estrogen levels and a pregnant person's urine can promote seed growth. 0:01:32.600 --> 0:01:35.199 What wasn't accurate was the attempt to determine the sex 0:01:35.240 --> 0:01:38.120 of the child based on which sprouted first, Barley for boys, 0:01:38.120 --> 0:01:43.160 wheat for girls. But still not bad and historians think 0:01:43.280 --> 0:01:47.400 this marked the beginning of medical urine examination and potentially 0:01:47.480 --> 0:01:51.680 laboratory medicine itself. More than three thousand years of urine 0:01:51.720 --> 0:01:55.720 examination also called eurro scopy or your analysis have followed, 0:01:56.280 --> 0:01:59.400 with varying accuracy. There was a bit of an expose 0:01:59.520 --> 0:02:02.320 in the sixty hundreds in London that called out fraudulent 0:02:02.360 --> 0:02:07.160 physicians using urine to diagnose pregnancy and lots of other conditions. 0:02:07.520 --> 0:02:12.080 The whistleblower referred to these frauds as piss profits. But 0:02:12.639 --> 0:02:17.560 urine research continued, and meanwhile, in the late eighteen nineties, 0:02:17.800 --> 0:02:22.280 scientists discovered the existence of hormones. A hormone is a 0:02:22.320 --> 0:02:26.399 product that sells make to regulate specific cellular activities such 0:02:26.400 --> 0:02:30.079 as cell growth and division, and in the nineteen twenties, 0:02:30.360 --> 0:02:35.000 scientists pinpointed a specific hormone called human choreonic ganado trop in. 0:02:35.639 --> 0:02:39.639 It's also called hCG because that's much easier to say. 0:02:39.960 --> 0:02:43.120 This hormone is found almost exclusively in the blood and 0:02:43.280 --> 0:02:46.280 urine of pregnant people, though we now know that certain 0:02:46.320 --> 0:02:51.440 cancers also produce it in anyone. But intrigued by this 0:02:51.520 --> 0:02:55.079 hormones linked to pregnancy, a couple of German researchers set 0:02:55.080 --> 0:02:58.560 out to develop a method of testing for hCG in urine. 0:02:59.440 --> 0:03:02.200 They decide to exploit the fact that hormones from one 0:03:02.240 --> 0:03:06.440 animal can generate biological responses in the bodies of other species, 0:03:06.880 --> 0:03:10.880 sort of like those sprouting seeds. They discovered that by 0:03:10.960 --> 0:03:14.760 injecting female mice with a pregnant woman's urine, they could 0:03:14.800 --> 0:03:18.000 stimulate the mice's ovaries and cause them to go into 0:03:18.040 --> 0:03:21.520 heat within a few days. They called this test the 0:03:21.600 --> 0:03:25.240 A Z test. Will note here that just as analyzing 0:03:25.400 --> 0:03:28.160 urine has a long history and medical science, so too 0:03:28.200 --> 0:03:32.480 has the use of animals. While often controversial and hopefully 0:03:32.520 --> 0:03:36.040 replaceable by technology in the future. A number of experiments 0:03:36.040 --> 0:03:39.880 on animals called bioassays, have led to important breakthroughs in 0:03:39.880 --> 0:03:45.600 medical science anyway, during the nineteen thirties, researchers applied the 0:03:45.640 --> 0:03:50.120 Azy tests methodology to two other species. In South Africa, 0:03:50.240 --> 0:03:54.280 researchers adapted it for use in frogs, inventing the hogbin test. 0:03:54.840 --> 0:03:57.400 The frogs would lay eggs if the urine they were 0:03:57.440 --> 0:04:01.880 injected with contained hCG. This test was used tens of 0:04:01.920 --> 0:04:05.080 thousands of times in the nineteen forties through the nineteen sixties, 0:04:06.240 --> 0:04:09.680 and at the University of Pennsylvania Medical School, one Dr 0:04:09.800 --> 0:04:14.360 Maurice Friedman made a breakthrough with rabbits similar to mice, 0:04:14.600 --> 0:04:18.239 If hCG is present in urine injected into female rabbits, 0:04:18.600 --> 0:04:21.640 the urine stimulates changes to the rabbit's ovaries within just 0:04:21.680 --> 0:04:25.640 a few days. The hCG basically fools the rabbit's body 0:04:25.760 --> 0:04:29.720 into temporarily thinking it's pregnant, and the rabbit's ovaries produced 0:04:29.720 --> 0:04:33.680 temporary tissue structures that a researcher can spot. The urine 0:04:33.680 --> 0:04:37.640 injection itself didn't harm the rabbit or the mice or frogs, 0:04:37.680 --> 0:04:40.960 but unfortunately, the fastest way to check the ovaries of 0:04:41.000 --> 0:04:45.440 the mammals was to euthanize and dissect the animal. Thousands 0:04:45.480 --> 0:04:48.600 of rabbits were sacrificed every year, to the point that 0:04:48.760 --> 0:04:51.720 the rabbit died became a euphemism for saying that someone 0:04:51.800 --> 0:04:57.279 was pregnant. The frogs, however, were unharmed and uh reusable. 0:04:57.960 --> 0:05:01.440 Luckily for the bunnies, though, The first immuno essay that 0:05:01.520 --> 0:05:04.719 could test directly for hCG and a sample of urine 0:05:04.960 --> 0:05:09.120 was developed in nineteen sixty. Immuno essays are tests that 0:05:09.279 --> 0:05:14.080 use specific molecules called antibodies that can bind onto whatever 0:05:14.160 --> 0:05:17.640 type of particle you're looking for in some detectable way. 0:05:17.880 --> 0:05:20.880 Maybe it makes the sample clump up, or maybe the 0:05:20.920 --> 0:05:23.719 antibody is attached to an enzyme that will change the 0:05:23.760 --> 0:05:28.040 color of a test strip from white to blue. And yes, 0:05:28.160 --> 0:05:33.039 today's at home COVID tests are also immuno essays. But 0:05:33.279 --> 0:05:36.479 it took over a decade to turn this initial discovery 0:05:36.600 --> 0:05:40.720 into something really usable for pregnancy testing. It involved a 0:05:40.760 --> 0:05:44.800 lot of research and societal changes, including advancements in prenatal 0:05:44.880 --> 0:05:47.880 care and the legalization of most abortions at a national 0:05:47.960 --> 0:05:50.520 level via the Supreme Court's decision in Roe v. Wade 0:05:50.520 --> 0:05:54.400 in ninety three, both of which incentivized being able to 0:05:54.400 --> 0:05:58.600 detect pregnancy as soon as possible. At that time, the 0:05:58.600 --> 0:06:01.159 best tests available had be sent away to a lab, 0:06:01.480 --> 0:06:04.599 and we're only reliable for detecting pregnancy at six weeks 0:06:04.680 --> 0:06:08.280 or later. The first home pregnancy test that's more or 0:06:08.320 --> 0:06:10.920 less equivalent to the ones we know today was approved 0:06:10.920 --> 0:06:13.320 for home use in nineteen seventy six and was on 0:06:13.400 --> 0:06:17.520 store shelves by early night. With the sample of urine, 0:06:17.520 --> 0:06:20.159 it could display a result within two hours, though it 0:06:20.240 --> 0:06:24.039 wasn't as accurate as early as today's tests are. A 0:06:24.160 --> 0:06:27.640 Modern pregnancy tests still involved detecting hc G, but have 0:06:27.760 --> 0:06:30.919 gotten more sensitive, meaning they can detect smaller amounts of 0:06:30.920 --> 0:06:36.279 it sooner in a pregnancy. Okay, a person's body starts 0:06:36.320 --> 0:06:40.919 producing hCG when a fertilized egg implants itself, hopefully in 0:06:40.960 --> 0:06:44.039 the prepared lining of the uterus. See our previous episode 0:06:44.040 --> 0:06:48.120 on how human conception works for more on that, but basically, 0:06:48.360 --> 0:06:51.919 under normal circumstances, a person will ovulate about a week 0:06:52.040 --> 0:06:56.320 after their last period, and if that ovulated egg is fertilized, 0:06:56.440 --> 0:07:00.599 it'll implant about a week after that. A so that's 0:07:00.640 --> 0:07:03.840 two weeks into a pregnancy, because pregnancies are calculated from 0:07:03.880 --> 0:07:06.840 the end of a person's last period, and that's when 0:07:06.880 --> 0:07:11.160 the pregnant body starts producing hCG. The presence and or 0:07:11.280 --> 0:07:14.120 levels of hCG in a person's body can be detected 0:07:14.160 --> 0:07:17.640 in two ways, via blood test or via urine test. 0:07:18.800 --> 0:07:21.400 A blood test is a little more accurate, but also 0:07:21.480 --> 0:07:24.960 more invasive. You have to get blood drawn and often 0:07:25.080 --> 0:07:27.680 more expensive. You have to go to a medical care 0:07:27.720 --> 0:07:30.240 provider to get your blood drawn and send the sample 0:07:30.280 --> 0:07:33.480 to a lab. But a blood test can detect the 0:07:33.480 --> 0:07:36.520 presence or quantity of hCG in your blood as early 0:07:36.560 --> 0:07:39.120 as two to three weeks into a pregnancy, and so 0:07:39.160 --> 0:07:41.640 before you would have ever missed your period, though it 0:07:41.680 --> 0:07:43.280 can take a day or more to get the lab 0:07:43.280 --> 0:07:46.920 results back. A urine test is more common because even 0:07:46.920 --> 0:07:50.120 though it's a little less accurate, especially early in a pregnancy, 0:07:50.400 --> 0:07:53.400 it's cheaper, can be done anywhere, and the results are 0:07:53.400 --> 0:07:56.920 pretty much immediate. These are done by either collecting a 0:07:56.920 --> 0:07:59.680 sample of urine and dipping a testing strip into the sample, 0:08:00.120 --> 0:08:04.080 or by urinating directly on a testing strip. A urine 0:08:04.120 --> 0:08:07.240 test can generally detect the presence of hCG three to 0:08:07.360 --> 0:08:10.840 four weeks into a pregnancy, so from slightly before to 0:08:11.080 --> 0:08:13.600 right after you would have missed your period, and the 0:08:13.640 --> 0:08:17.400 results develop on the strip within a few minutes. These 0:08:17.400 --> 0:08:19.880 tests do very a little, so if you're taking one, 0:08:20.040 --> 0:08:23.600 just read and follow the instructions, but rest assured that 0:08:23.640 --> 0:08:34.679 there will be no rabbits, frogs, or barley involved. Today's 0:08:34.720 --> 0:08:37.000 episode is based on the article how can a Rabbit 0:08:37.080 --> 0:08:39.040 Tell Me If I'm pregnant? On how stuff works dot 0:08:39.040 --> 0:08:41.960 com written by Robert Lamb. Brain Stuff It's production of 0:08:42.000 --> 0:08:44.240 I Heart Radio in partnership with how stuff works dot Com, 0:08:44.320 --> 0:08:47.360 and it's produced by Tyler Klang. Four more podcasts from 0:08:47.360 --> 0:08:50.440 my heart Radio visit the iHeart Radio app, Apple Podcasts, 0:08:50.520 --> 0:08:52.319 or wherever you listen to your favorite shows.