There are a wide variety of options available for you when you go shopping for a
home pregnancy test (HPT). This page will help you figure out when to take one,
how they work, and what brand will offer you the best results.
The Science Behind Home Pregnancy Tests
Pregnancy tests look for the presence of a hormone called "beta hCG." hCG stands
for human chorionic gonadotropin, and it is produced as soon as implantation of a
blastocyst occurs. (You can read more about this here.) The levels of hCG within
the woman rise very quickly, doubling every 2 to 3 days. When you take a pregnancy
test, the hCG in your urine (if present) will react with a chemical in the pregnancy
test, creating a positive result.
When to Take a Home Pregnancy Test
With a very sensitive pregnancy test, the earliest possible time you can get a positive
test is 7 days after ovulation. The blastocyst implants in the uterine lining on
average between 7 and 10 days after ovulation occurs. (This is anywhere from 1 week
to a few days before your period is due if you have a normal 28-day cycle.) As soon
as the blastocyst implants, it begins to produce hCG. However, you're better off
waiting until at least 10 days after ovulation just to give it enough time. If your
baby is a late-implanter, you may not show a positive pregnancy test until after
your period is due. Confused? The easiest plan of action is to buy 2 tests. Take
one 10 days after ovulation (a few days before your period is due). If it is negative,
wait to see if your period comes. If it does not come, wait 3 more days and take
the second test. By then, it should be positive if you are pregnant.
How to Use a Home Pregnancy Test
It is important to follow all the directions on your pregnancy test. Here are some
You only need to use first-morning urine if you are testing early in your cycle.
The later in your cycle you test, the more likely that hCG is going to be present
in high numbers, making it more likely that you would get a positive result any time
of the day. However, if you can use first-morning urine when you take your test,
You should avoid drinking a large quantity of liquids prior to taking the pregnancy
test. You don't want your urine to be too "watered down" and end up diluting the
hCG. If you've had a lot to drink, empty your bladder and then avoid drinking large
amounts for the next 2 to 3 hours. Then take the test.
Even if the positive result (whether it is a plus sign or a line, etc.) is very,
very faint, it means you are pregnant. A faint positive result just means that you
have a lower level of hCG than someone who would turn it positive immediately.
Only read the test within the time window given to you in the instructions. Some
tests will turn positive after they have sat awhile.
Home Pregnancy Test Sensitivity Comparison
It's important to know the sensitivity level of your pregnancy test - in other words,
the level at which your pregnancy test will detect hCG in your urine. Some tests
are able to detect a low level of hCG, while others will only turn positive if there
is a larger amount of hCG present. The tests that require the lowest amount of hCG,
measured in mIU, are generally better, since they will give you more accurate results.
Therefore, take a look at the following list of the most common pregnancy tests,
and use it to plan your purchase.