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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 general tips:

  • 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, do so.
  • 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.


20 mIU

AimStick Pregnancy Test Strip


New Choice (Dollar Tree)


25 mIU

Answer Early Result

Baby Test (Dollar Store)

Clearblue Easy +/-

Clearblue Easy Digital

Confirm 1-Step

CVS Early Result

e.p.t. +/-

e.p.t. 1-Step Digital

e.p.t. Certainty Digital

Equate (Wal-mart)

Fact Plus Midstream

First Response Early Result

One Step Be Sure

Rite Aid Pregnancy Test

Target Brand Pregnancy Test

Walgreens Midstream

Walgreens Digital


40 mIU

Fact Plus Cassette


50 mIU

Clearblue Digital

CVS "Early Result" Cassette

Dollar General Store Pregnancy Test

Drug Emporium Brand Pregnancy Test

Family Dollar Pregnancy Test

Walgreens Cassette Pregnancy Test

Home Pregnancy Tests