Comments

You must log in or register to comment.

footyDude t1_iua9wwa wrote

One reason would be so they can easily manufacture and sell the same test in multiple international markets without having to do any localisation.

That said, some do come with written-language results (at least in the UK a lot of the 'digital' ones will show 'pregnant' as a result).

422

jumpsteadeh t1_iuarxhs wrote

"better not tell you now"

67

SunnivaD t1_iuau8ze wrote

"Try again later"

60

pierrekrahn t1_iub08uz wrote

"Outlook not so good"

49

Moln0014 t1_iubf5yv wrote

Fortune cookie says expect to meet someone new in 9 months

18

corey_m_snow t1_iuaa8d1 wrote

It depends on the test, but the basic principle is that you have a piece of paper that absorbs liquid and "wicks" it through the fibers. At one end that paper is exposed to a stream of urine that is absorbed into the fibers.

At the other end of the paper is a diagnostic strip that will change color or darken if certain chemicals are present and will not change if they are not- that's looking for the presence of specific substances that are only present when someone is pregnant. There's usually a second strip that's a "control" and will change color regardless of the presence of any chemicals.

So when you use the test, the liquid is absorbed up the paper, wets the two strips, one will turn color letting you know that the test is working and that enough liquid got into the tester that the result is valid, and if the other one changes it's a positive result.

All that said, some testers do have digital readouts. I'm not familiar with how those work, but they cost a bit more, from my understanding.

110

deusrex_ t1_iuajegk wrote

I'm pretty sure the digital ones work exactly the same way, and use a sensor to look at the stripe to see if it changed and just print on the screen the result of the strip.

66

Raisinhat t1_iub1qv7 wrote

Spoiler alert: that is exactly how they work

41

hypermog t1_iub84r0 wrote

I see in one of those tweets that the CPU in this pregnancy test is faster than my family’s first personal computer

9

nerdguy1138 t1_iub94r2 wrote

And it can run doom!

7

arcosapphire t1_iubxfw3 wrote

Well, the one in the teardown thread specifically can't.

3

Exist50 t1_iubyebv wrote

IIRC, that guy just replaced the internals with ones that could run Doom, sadly.

2

kasteen t1_iuc0izz wrote

>As Turing explains, the test's "existing CPU can't be reprogrammed and the existing LCD can only show 4 things, so I had to replace both to make any changes. And the current version doesn't even fit into the shell! (although I'm certain it will when complete)."

It isn't running on the hardware from the pregnancy test at all. It's just a computer that may or may not fit inside of the test.

2

arcosapphire t1_iubxe0l wrote

That thread was super cool. Is there a subreddit for "how they work" kinds of things like this? I mean obviously this person does stuff like that on Twitter, but I have always hated Twitter's format and never know how to navigate things properly. (Plus now it's a total shitshow with the recent corporate drama.)

2

TurnstileT t1_iuasycb wrote

That sounds.. very unnecessary and wasteful to manufactory disposable electronics for that purpose.

30

leahlisbeth t1_iub1bh8 wrote

I took one apart once, I can confirm this is exactly how they work

14

colimar t1_iuazqsg wrote

But can run doom

4

julie78787 t1_iub2zsp wrote

A lot of smaller microcontrollers have all the hardware needed to run old text-only games. Often all that's needed to interface to an old serial terminal is the voltage converters.

I am not going to program a used pregnancy test to play doom or moria or any other text-only game.

4

Canadian__Ninja t1_iuab5yb wrote

It's cheaper to make it without the text, both from a tech standpoint in that it's more work and because you don't need to understand language x to be able to use it. I don't have experience with them but I'd imagine a French woman would be able to seamlessly use a pregnancy test made in Czechia for instance.

94

MembershipFew989 t1_iuamqof wrote

After 2 years of COVID does anyone really struggle to read a 2 line LFT test?

30

Ahnamal t1_iubiit2 wrote

Well but sometimes the line is really faint and also you can to some degree track how the pregnancy is progressing by testing over repeated days to see a progression in darkness. HCG, the hormone that they test for, is supposed to double every day. So especially if you’ve had losses in the past, it can be very reassuring to see a darker and darker line. Sometimes the test line will even pull die from the control line, those are called die stealers.

3

dexable t1_iubs42y wrote

Funny you mention this I had to teach my husband how to read a COVID test the first time. I understood it immediately because of the pregnancy tests I took to make sure I wasn't pregnant prior to the pandemic.

1

Glum_Butterfly_9308 t1_iub9vte wrote

There are some digital tests now that say “pregnant” or “not pregnant” (and also some kind of digital ovulation tests - I think they flash a smiley face if you are ovulating).

They are more expensive, wasteful, and would have to be different in every language.

The way the test usually works is that it responds to a hormone you produce while pregnant. If that hormone is present, you will see two lines. If you’re not pregnant you will just see the control line. This is very rudimentary - making a test with a digital screen is a lot more complicated.

People who are actively trying to have a baby may take dozens of tests over that time. They usually buy a box of cheap tests that are literally just a tiny strip you dip in a cup of urine (as opposed to a big plastic one you can pee directly onto)

14

osc515 t1_iuaq9ni wrote

Same reason why US only cars have descriptions next to the wipers, lights etc. and international brands use symbols

5

HotLips4077 t1_iuarlpz wrote

They do! They are the digital ones that usually say Yes+ or No- So they definitely make them. Clear Blue Easy or most generic brands are available but be prepared to shell out a few extra bucks for the tech :)

5

tdscanuck t1_iuaff69 wrote

Also, “yes” or “no” is ambiguous. “Yes, you’re pregnant” or “Yes! You’re not pregnant.” You want “pregnant” or “not pregnant”, but you don’t want to have to do it in every language.

4

PracticalCategory888 t1_iuawsdg wrote

Symbols? A plus for positive and a minus for negative?

3

PeeledCrepes t1_iub24hj wrote

Or 1 line for it's just you 2 lines for its you and your baby?

6

b00tyqu33n29 t1_iubd2rh wrote

Don’t get a test, get a box of the little tab testers online. You can get a box with a ton of them for $10. Break open one of the “cheap” $7 single tests and you’ll probably find the same slip of paper inside. It’s a waste of money to buy the single ones when you can just have a box and rip open the foil super easily when you need one.

2

tweakingforjesus t1_iube2t6 wrote

How often do you test for pregnancy? Even when we were trying to get pregnant we used maybe one a month.

1

Glum_Butterfly_9308 t1_iubi9ou wrote

Not everyone has an easy time conceiving. Some people take years, and eventually those tests add up.

Personally it took us 20 cycles before we had a single positive. I had lots of months where I didn’t test at all, some where I tested once, some where I really had a feeling they were it and I tested a couple of times (testing early can give a false negative).

It is common when you do finally conceive to keep testing and watch the lines get darker. Many people have chemical pregnancies. These are very very early miscarriages that we only know about because the tests have gotten so good. Back in the day where you had to wait several days to a week after a missed period to test, you would never even know that you had a chemical. Now, you may get an early positive but have the lines get lighter over the next few days. If you’re having fertility struggles, it’s helpful to know whether you are conceiving and losing pregnancies early or not conceiving at all.

When we did conceive I think I took about 4 tests over the course of a few days but online I often see people do 6-8. Many people will test until they get a “dye-stealer” which means that the test line is darker than the control line. People take this as a positive sign that it is progressing well.

4

tweakingforjesus t1_iubk05l wrote

Wow. We thought we might have trouble but it went pretty smoothly for us. I’m glad we didn’t have to go to such lengths.

3

[deleted] t1_iubq00n wrote

[deleted]

−3

tweakingforjesus t1_iubrdhl wrote

I’m very sorry I came off like that. That was not my intention. I was trying the state that I recognize how difficult it can be and I understand how lucky we were. We were preparing for a multi year effort and even began early to try to have a better chance with the challenges we were expecting. My wife used those ovulation dipsticks and we scheduled specific days of the month for quality time. We even had a referral to a fertility specialist ready for when that time came.

I am very sorry for what you had to go through. I honestly wish you well.

3

dexable t1_iubt6ym wrote

There are other reasons to test for it on the regular. Like if you have an irregular cycle or your period is late. The number of times I used pregnancy tests when i wanted a negative result greatly out number the times I was checking for a positive result.

3

will477 t1_iublq1v wrote

They should just have two LEDs. One red and one green. When the light is green, the trap is clean.

2

saltfish t1_iubb8uk wrote

The digital ones are the same as the ones with the lines, they just use additional electronics to read the lines and give you the lcd output.

1

Flair_Helper t1_iuc73qo wrote

Please read this entire message

Your submission has been removed for the following reason(s):

Loaded questions, or ones based on a false premise, are not allowed on ELI5. A loaded question is one that posits a specific view of reality and asks for explanations that confirm it. These usually include the poster's own opinion and bias, but do not always - there is overlap between this and parts of Rule 2. Note that this specifically includes false premises.

If you would like this removal reviewed, please read the detailed rules first. If you believe this submission was removed erroneously, please use this form and we will review your submission.

1