For many years, home pregnancy tests have been most women's
first choice to confirm their suspicion they might be pregnant.
Home pregnancy tests are inexpensive, disposable kits available
over-the-counter from most pharmacies, some supermarkets also sell
them and they can also be purchased online.
Using a home pregnancy test is a great way to choose a time and
place where you're most comfortable, before getting a pretty
accurate result on whether or not you are pregnant.
What is a home pregnancy test?
Home pregnancy tests are sensitive, once-off test kits that
respond to the presence of a hormone called human chorionic
gonadotrophin - hCG - in urine. This hormone is released when the
fertilised egg first implants in the uterus, usually between 8 and
10 days after fertilisation has occurred (though it can be anywhere
from 6-12 days!)
Levels of hCG will rise quickly in the first few days after
following implantation and peak between 50 and 80 days after
fertilisation. Within about two weeks, usually when your period is
due, the hormone can be easily detected in urine.
Some home pregnancy tests are highly sensitive and can pick up
quite low levels of hCG in urine, giving a response up to a week
after implantation.
More sensitive tests are usually more costly and will detect a
concentration of 20 mIU (which is about 20 parts per one thousandth
of a millilitre); while the stock-standard tests will only give a
result when there is 50 mIU - which will happen a few days
later.
The sensitivity of the home pregnancy test will be marked on the
box; the most popular tests are currently 20, 25, 40, 50 or 100
miU.
How do I use a home pregnancy test?
Home pregnancy tests come with detailed instructions and
information, and it's wise to follow the instructions
carefully.
You can usually perform the test any time of day, and use the
test from the first day that your period was due. Many women choose
to do the test first thing in the morning, when the hormone levels
in the urine are likely to be at their highest.
Test results can be affected by fertility drugs containing hCG
hormones and can also be affected if you have had a lot of fluid to
drink shortly before taking the test - as this can dilute the
urine. But other medications are unlikely to affect test
results.
Home pregnancy tests differ in the way that they need you to
collect urine.
For some home pregnancy tests, the plastic stick containing the
test strip should be held a few centimeters underneath you, while
you wee directly onto the stick; other tests supply a small plastic
container for collecting the urine, which you then put onto the
test stick with a dropper.
The way that the test results appear, will depend on the way the
manufacturer prepared the kit. Do check the instructions carefully
to see what to expect.
In many tests, the response will appear as two lines, parallel
or crossed. One "control" result line will ALWAYS appear; but the second result line will
only appear in response to the presence of hCG - so that's two
lines for pregnant, one line for not pregnant.
Some tests reveal a plus or minus sign, or spell the words
'pregnant' or 'not pregnant;' and some change colour; test results
might be red, pink or blue.
Most tests will give a result in five minutes. Try to find
something to occupy you for that five minutes, as it will seem like
an eternity! It's excruciating to sit there and watch the test to
change.
How accurate are home pregnancy tests?
Most home pregnancy tests are around 97% accurate, provided that
you follow the instructions exactly. If you have a very irregular
cycle, it can be difficult to determine whether the time is right
to test.
False negatives (when you are pregnant but the test doesn't show
this) occur if you test too early, or if your body is not making
the expected amount of the hCG hormone.
If you get a negative result but you still feel you might be
pregnant, wait three days then try another test.
False positives (when the test says you're pregnant but you're
not) might occur if you have taken a fertility drug which contains
hCG or if there is an error in the test.
Many doctors use urine tests that are exactly the same as home
pregnancy tests to verify pregnancies. However, if there is some
uncertainty about results, your doctor may order a blood test which
will also test hCG levels, but is usually more sensitive than a
urine test.
Tips for performing a home pregnancy test
- Before you do the test - think about whether you are doing it
at the right time and if you would like to have anyone (such as
your partner) with you at the time you do the test.
- Most importantly - read the directions carefully, even if you
have done a home pregnancy test before, because every brand will
have slightly is different requirements
- Try not to do the test too early for two reasons; first, you
might get a false negative. And second, because around 25% of
pregnancies miscarry, most in the first few days,- you may be
unfortunate enough to detect a very early pregnancy that doesn't
"take" - and experience the emotional journey of miscarriage at a
very early stage.
By Fran Molloy, journalist and mum of four