What factors can make a false positive appear on a home pregnancy test?

Question

Serious answers only please. I'm really worried, but also really confused. Don't need support, & will go go 2 the doctor 4 a blood test. But I just wondered if any1 could tell me now? I'm being prescribed lots of different medication at the mo. May that have caused this? The missed period I could put down 2 stress & not eating, but the positive just doesn't add up with my dates?!

Answer 1

firstly i kinda know wot your talking about.
I am currently5 wks pregnant, all my urine samples came up positive but my blood sample came up negative at the hospital, of course based on these blood results the Dr at the hospital told me i wasnt pregnant and sent me home totally confused.
15 home pregnancy tests later (all of which were positive) i went to my GP who performed yet another urine test that came out positive!!
When i questioned the Dr on the blood test he infomed me that the blood and urine test measure the amount of HCG hormone in your system, however certain pathology labs test blood in different ways, one test give you a yes/no answer the over test (qualitive) actually measures the amount of HCG in your blood, depending on the area you live in this is measured at different levels (ie 05mlu, 10mlu and 25mlu) were i had my blood test they measure as under 10mlu as a negative.
When buying your home test kit check to see what level of HCG in your urine is classed as a positive, in my opinion go for the one with the highest level (i used first response although a cheaper substitute is the tesco home branded one which also measures as over 25mlu as a positive) if you use one of the higher level test ones the likelyhood of you being pregnant is extremly high as you have to a high level of HCG hormone in you urine and these test very rarely cause a false positive result.
Also after much searching on the net i discovered the only things that can cause false positives are prescribed medications for fertility and very rarely certain cancers of the reproductive organs

Answer 2

As far as I know a positive means pregnancy! You can have a false negative if the test fails to detect the HCG hormone in your urine (because your urine is too dilute or you test too early) but its impossible to have a false positive.

A positive pregnancy test means that HCG hormone is present in your urine, to a large enough level to be detected by a test.

If you have a faint positive that then turns to a negative on future tests -that is not a false positive but a "biochemical pregnancy" - where fertilisation and implantation has occured but it is not well established enough to stick, and is lost in a slightly delayed period (ie a very early miscarraige) shortly afterwards.

The only instance I've ever heard of false positives is sometimes if a woman has had IVF. They give her HCG hormone injections in the early stages of the IVF procedure to suppress her natural hormone cycle. Sometimes if the test is performed too early after egg transfer the residual HCG can stil be hanging around in her system and can cause a false positive. But even this is rare.

You could always check with your doctor if you're convinced you are not pregnant, but all I can say is that ts very rare if not impossible to get a false positive on a HPT!

PS don't wory about what Meg D says that nonsense. Most women have taken medication in the very early stages of conception - before they even find out they are pregnant and their babies are fine. Thats just a nasty scaremongering comment to make and its not true.

Answer 3

The older birth control gave a false positive. If you're taking HGH (human growth hormone), also called 'stacking' by bodybuilders, it can give a false positive. You may want to go to the doctors and get a blood test for pregnancy. Generally if it says positive, you are. A sperm can live up to 3 days in the female body, and an egg can live 5 days traveling to the uterus, so your dates may not be accurate.

Answer 4

What do you mean by your dates don't add up? If a home preg test comes up positive, try another 1. If more then 1 comes up positive, then your pregnant. A positive result is mostly always correct, wheras a negative can be wrong. Go to the docs to make sure, and put your mind at rest, because you can't accidentally (or deliberatly) fool a preg test, whether its a home one or not. Good luck!

Answer 5

False positive will not happen with a home pregnancy test only false negatives.

Answer 6

False positives happen less than 1% of the of all the wrong test results that are received every year. Basicly, the test would have to have been defective. So, chances are if it was positive....you're pregnant! Remember, you can get pregnant any time of the month! It doesn't have to be the exact 3 days between your cycles. Especially if you're stressing, you could have completely thrown ovulation out of wack! Good Luck, congrats!

Answer 7

I have always heard that some home pregnancy tests may give a false negative, but very rarely do they give a false positive. Chances are, if it is positive, you may be pregnant.

Answer 8

It would depend on what kind of meds you are on. I have heard that a false positive on a HPT is rare, but false negatives are common. If the test was expired, or if you let it lay around for too long a time before reading it. Those things could cause a false positive.

Answer 9

Forget your dates, they prove nothing but sometimes help work out when you are due. The pregnancy test looks for a very specific chemical which is only produced if you are pregnant so it's not false- you are pregnant. Good luck x

Answer 10

It could be an evaporation line,I had one and thought that I was pregnant.I've also known someone who had a "chemical pregnancy" although I'm not exactly sure what it is.They got a positve but weren't pregnant.
Check out peeonastick.com. They have loads of information on pregnancy tests.