The answer is that any visible line in the 'result zone' – no matter how faint – indicates a positive pregnancy test. We have all got used to watching for lines on Covid lateral flow tests and the same is true there: if there is a line, no matter how faint, it is a positive test.


So how faint is very faint?

Obviously, everyone has a different idea of what a faint line looks like but we're talking anything from not very obvious to proper put-your-specs-on-and-peer-at – as you can see from our main picture of 6 different positive pregnancy tests (some done with multiple test strips) posted on our MadeForMums Chat forum.

I know how hard it can be sometimes to tell if it's a line or not. When I was trying to conceive, I remember squinting at pregnancy tests trying to work out if there was a faint line or not. In fact, I always asked my husband to check – and then I admit I may have sometimes done a repeat test to be sure!

Why is the line so faint?

If the line is faint, then it is likely that you are testing very early on in your pregnancy.

A pregnancy test is designed to show a line if it detects, in the urine you dipped it into, a threshold level of a hormone called human chorionic gonadotrophin (hCG). Levels of hCG rise rapidly in the early weeks of pregnancy, are at their highest at about 10 weeks of pregnancy, and then slowly fall again.

But if you're taking the test very early on in your pregnancy, your levels of hCG will be small, meaning that, although there is enough for be detected by the test kit, it is only enough to create a faint line.

More like this

Can a faint line ever mean I'm not pregnant?

A false positive pregnancy test is extremely rare ("false positive" means the test is positive but you are not actually pregnant). That's assuming, of course, that you haven't used a test that's past its expiry date or are 'reading' the result long after the wait time outlined on the packet.

A false positive can occur if you are on particular medication, such as a fertility drug containing hCG, or if you have a medical condition, such as an ovarian cyst, which can raise your hCG levels. A pregnancy test may also be falsely positive if you have recently had a miscarriage or termination of pregnancy, as it takes a little time for the hCG levels to fall.

It is also possible that you can have a genuinely positive pregnancy test and then, a few days later, if you test again, it's negative. This is because urine home pregnancy tests are extremely sensitive and can pick up a pregnancy in the very early stages – and, unfortunately, not all pregnancies progress past these very early stages. If the pregnancy doesn't progress, then a new test will show as negative. This is called a chemical pregnancy – or a very early miscarriage – as it tends to occur before a heartbeat can be seen on the scan, so before approximately 5 or 6 weeks of pregnancy. In this situation, bleeding tends to start soon afterwards but, if it does not, then please see your doctor.

So if I get a faint line, should I do another test?

Yes, that's what I'd recommend – but leave it a couple of days or so. Levels of hCG double every 48 to 72 hours in the 1st weeks of pregnancy so the line on the pregnancy test may be stronger when you test in a few days' time.

I'd also recommend that you make sure you do the pregnancy test the first time you wee that day as that's the time of day when your wee is likely to be more concentrated.

What's hCG exactly – and how do pregnancy tests work?

HCG is a hormone that's made initially by the embryo itself, and then by your placenta, and has various roles, from supporting the corpus luteum (what is left when the egg is released) to supporting implantation.

The pregnancy test works by absorbing your urine onto the pad or strip of the pregnancy test and, if there's hCG present in that urine, it will bind to antibodies which are attached to the coloured dye in the test that forms the blue or pink test line – and make that line show up. If there is no HCG present in your urine, and you are not pregnant, there are no antibodies to bind to the dye, so no line forms.

There is generally a control line in a pregnancy test to check that the test is working. In a positive pregnancy test, both the test line and the control line should be seen.

About our expert Dr Philippa Kaye

Dr Philippa Kaye works as a GP in both NHS and private practice. She attended Downing College, Cambridge, then took medical studies at Guy’s, King’s and St Thomas’s medical schools in London, training in paediatrics, gynaecology, care of the elderly, acute medicine, psychiatry and general practice. Dr Philippa has also written a number of books, including ones on child health, diabetes in childhood and adolescence. She is a mum of 3.

Pics: taken from the MadeForMums Chat forum


Read more