How Do Pregnancy Tests Work? — Transcript

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1. 0:00This video is dedicated to all the women out there who are late and ready to know the truth.
2. 0:04Whether it was planned or not, the only way to know before the old fashioned way is by
3. 0:08using a take home chemistry kit that you know as a pregnancy test.
4. 0:12But how does a little strip of paper and a few drops of urine  tell you whether or not
5. 0:17you’ve got a bun in the oven?
6. 0:18Let’s find out.
7. 0:19(Splash) When a woman becomes pregnant, hormones start
8. 0:23sending chemical signals to prep the body for the tiny person who will be taking up
9. 0:27a nine month residency inside.
10. 0:29One of the first hormones produced is human chorionic gonadotropin, or hCG for short,
11. 0:35and this is what pregnancy sticks are designed to detect.
12. 0:39Pregnancy tests have three main sections: the place to pee on, the place where the main
13. 0:42chemistry happens, and a control to make sure you can be confident in the results.
14. 0:47There’s some pretty tricky chemistry that goes on during the test, so what we’re going
15. 0:50to do is show you both a positive test (test1) and a negative test (test 2) side by side
16. 0:54for comparison.
17. 0:56After pee is applied to the first part of the test stick, capillary action causes it
18. 1:00to slowly flow through to the other end.
19. 1:03First it passes through a thin strip loaded with mobile antibodies that are taken up by
20. 1:07the pee, and are designed to bind to hCG.
21. 1:11These antibodies are also equipped with a special piece of cargo that’s put to use
22. 1:15later on in the test, but we’ll come back to that later.
23. 1:18If hCG is present like in test 1, the antibodies start binding to it, and move through the
24. 1:23test as a unit - unlike in test 2, where the antibodies move through on their own.
25. 1:28At this point, you can’t actually see anything happening.
26. 1:30But that’s about to change as the pee flows to the next section, which we here at Reactions
27. 1:35like to call the antibody test-forest.
28. 1:38Each individual tree in the test-forest is an antibody rooted in place that’s specially
29. 1:43designed to grab onto a different part of the hCG.
30. 1:46So when the pee in test one passes through, the hCG-antibody pairs get trapped in the
31. 1:51branches of the test forest, where that extra piece of cargo comes into play.
32. 1:55And as more and more hCG-antibody pairs get stuck in the forest and begin building up,
33. 2:00that dye becomes more and more visible to the naked eye.
34. 2:03And that’s the blue line you see if you’re pregnant.
35. 2:05-  The urine in test 2 on the other hand, with solo mobile antibodies in it, flows right
36. 2:09through the test-forest undetected.
37. 2:12But that leaves test 2 a bit high dry, don’t you think?
38. 2:16How can they be sure that say, their test strip wasn’t ripped, cutting off the urine
39. 2:19from reaching the antibody forest, or that the mobile antibodies really were taken up
40. 2:23by the pee?
41. 2:25For this reason, manufacturers add a control -- another antibody forest downstream from
42. 2:30the first one, that we’ll call the control-forest.
43. 2:33The control-forest is exactly like the test-forest, except instead of having antibodies designed
44. 2:38to detect hCG, they’re actually designed to detect the mobile antibodies!
45. 2:42So in both test one and test two, the branches of the control-forest grab onto the mobile
46. 2:48antibodies.
47. 2:50As they build up the dye on the special cargo becomes visible, and the control line appears.
48. 2:55All functional pregnancy test should have the control line appear.
49. 2:58If it doesn’t, it means something messed up the test result, and you’ll have to try
50. 3:02again.
51. 3:03If both lines light up, there is a 99%+ chance you’re pregnant.
52. 3:07If you think you’re pregnant but the test is negative, wait a few days and try again.
53. 3:11We here at Reactions want to wish a happy mother’s day out there to all those incredible
54. 3:15women who got the blue line, and brought us into this wonderful, chemistry filled world.
55. 3:20We want to see some love for moms down below people, don’t be shy!
56. 3:23Thanks for watching.