Follow-up blood tests will be able to tell whether your hormone levels are dropping or rising.2) Evaporation lines Sometimes an 'evaporation line' can appear on a test as urine dries in the test window, and some women may confuse it for a very faint second line.
It's most likely to show up when a test is viewed after the recommended reading time has passed, and it can be a different colour to the line that will appear with a positive result.
An expired test could give an inaccurate result if the dyes that are used for the test and control lines have faded, or if the chemicals are no longer strong enough to detect h CG.
A test can also be faulty if it has been stored in a hot or moist area (such as the bathroom), in an open box.
Women who are hoping to fall pregnant again soon after a miscarriage may be disappointed to realise that a positive test doesn't necessarily mean they are pregnant again, as it can take a while for hormones to return to their pre-pregnancy levels.1) A dirty cup If you collect your urine in a cup you've used for a test before - if the cup still has traces of old urine, soap or water - the results can be affected.
Use a new cup or buy a pee stick test instead.2) Expired or faulty test Always check the use-by date on a test.
1) Testing too soon Being able to test so early nowadays doesn't always mean you'll get an accurate result on the first day you can test.
If you're taking any of these you might be warned to wait until the medications are out of your system before taking a test.4) Underlying medical problems Certain medical conditions can affect pregnancy test results, whether or not you're been diagnosed before falling pregnant.
For example, if you have a UTI or kidney problems, blood or protein might be in your urine, which can change the test result.
It's best to do a pregnancy test in the morning when your urine is most concentrated.4) Testing late in pregnancy This is very rare, but sometimes if a woman takes a test at the end of her first trimester or later, the test might not detect h CG, as her levels may be higher than the test is designed to pick up.
This is called "the hook effect" and could explain why some women believe they're not pregnant until they give birth, even if they do take a test.1) Chemical pregnancy A positive test doesn't always mean a pregnancy is viable.