Helping parents make confident choices

Pregnancy Test – Positive then Negative?

Is it possible for a pregnant test to be wrong?

When you are trying to conceive it can seem like your body is playing all sorts of tricks on you.
A heightened sense of what might be going on inside you means you become more sensitive to mild aches and pains, and the stress of waiting to find out each month is you have successfully conceived can possibly delay your period and raise your hopes falsely. Indeed, one of the most common questions asked here on ThinkBaby is what it means to have: no period but a negative pregnancy test.


Could my pregnant test be wrong?
Most test kits nowadays are incredibly reliable and will allow you to find out that your are expecting long before you get official results back from a urine test at your GP's surgery.

However, it is important to note that you should adhere to the instructions that come with the kit you buy.
Tests work by looking for levels of a hormone (HCG) which is produced when you are pregnant. The amount of this hormone increases each day after you conceive and, if your regular cycle is about 28 days, this means that by the time your next period is due, you may well have two weeks' worth of this hormone present to be detected in your urine sample (given that your most fertile point is half-way through your cycle). So – if you pick a test kit which can only detect a minimum of about 50mlU of this hormone, you will need to wait longer to use if after your possible conception than if you bought a kit which can detect 25mlU of the hormone.

If you use a test kit too early, it might not be able to reliably give you the right result because it can't pick up the levels of HCG accurately.
In addition to this, it is estimated that about 50 per cent of ALL conceptions do not establish as pregnancies because a fertilised egg may not successfully implant in the womb. You might not even physically notice that you have lost the fertilised egg, yet it could send mixed hormonal messages which mean you get a faint but positive message from one test but then either get your period a few days later or get a negative test followed by your period.


For more about the various options you can choose from when selecting a kit, read our Buyer's Guide to Pregnancy Test Kits.


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