Peeing on a Stick: All About Pregnancy Tests
As you stand in front of the aisle of pregnancy tests at your local drug store or chemist, you’ll likely notice a couple of things. First, there are a heck of a lot of choices! There are rows and rows of colorful boxes to choose from. In recent years, the numbers and types of pregnancy tests available in most areas have really boomed. Secondly, as you look at the boxes, you’ll probably notice how difficult it is to figure out exactly which test may be “best” for you. Which test is going to be most accurate? Do I need one test or two? What about these digital models? Do I need a brand name or is a store brand good enough? Should I even be taking a home pregnancy test or would it be better to go see my doctor?
All of these options can be confusing for anyone, especially so if you are in a hurry or are very worried. Whether you are hoping for a negative or positive result from a pregnancy test, it may be helpful to know a little bit about pregnancy tests before you head to the store or to your health care provider’s office. This article is designed to give you a general overview of pregnancy tests. It will discuss what a pregnancy test does, the difference between a urine test and a blood test, how to choose a pregnancy test, when and how to use pregnancy tests, and finally what to do after a pregnancy test.
So what is a pregnancy test anyway?
Whether you are taking a urine test or a blood test, pregnancy tests look for one thing, human chorionic gonadotropin (hCG). When you see television commercials that talk about “the pregnancy hormone,” they are referring to hCG. This hormone is only present when a person is pregnant. The body will start producing this hormone once a fertilized embryo implants in the uterus. (You can find out more about the reproductive process in our article Human Reproduction: A Seafarer's Guide.) The process of fertilization and implantation takes several days to complete. It will take several more days for the body to produce enough hCG for it to be detected by a pregnancy test. (In general, the level of hCG doubles about every 72 hours after conception for the first several months and will then level off for the remainder of the pregnancy.) This means that a pregnancy test is not going to be accurate if taken immediately after (or even a few days after) sexual activity, because there would not be enough of the hormone present for a test to find it.
Because pregnancy tests look for this very specific hormone, the result of a pregnancy test is not going to be impacted by foods, medications, or other things. The only known exception to this is medications that are sometimes used to treat infertility. These medications can contain hCG.
What is the difference between a urine pregnancy test and a blood pregnancy test?
All home pregnancy tests (HPTs) that you can purchase online or at your local store are urine pregnancy tests. Because they are so affordable, many health care providers’ offices will also use these urine tests. Each urine test is “set” to check for a certain level of hCG. Different types and brands of tests check for different levels, but generally tests are set to check a level somewhere between 15 mIU/ml and 100 mIU/ml. The lower the set level the test checks for, the sooner a test would be able to give a positive result. You’ll find that many tests labeled for “early results” or “early responses” will look for levels around 15 or 20 mIU/ml. So, if you use a test that is set for a 25 mIU/ml level (like your average test is going to be), you could expect to receive a positive result once the hCG in your body is at or over that level. This does not mean that a test that is more sensitive is necessarily “better” or “more accurate” than one that looks for a higher level of hCG. It does mean that you can get a positive result sooner with a more sensitive test.
There are two common types of blood pregnancy tests. The first type of test is similar to a urine pregnancy test. This qualitative test asks whether or not hCG is present at a pre-set level for the test. This type of test essentially provides a simple “yes” or “no” answer to whether you are pregnant or not. The second type of blood test is referred to as a quantitative test. This test will tell your health care provider the exact amount of hCG in your blood at the time the test is done. The primary benefit to this type of test is that it can help a provider begin to establish not only that a patient is pregnant, but approximately how long they has been pregnant.
There are so many choices, how do I choose the right test?
Your first choice when it comes to pregnancy tests is whether you want to take an HPT or go to your health care provider for a test. HPTs are easily available at your local drugstore, chemist, grocery store, or big box retailer. They are also fairly inexpensive (generally ranging from around $6.00-$20.00 depending on the model). Many women may feel that an HPT is more private because you can take it at home or anywhere else where you can find a bathroom and get the results in a matter of minutes. The downside is that it is up to you to make sure that you have taken the test correctly. Some people may also feel unsure about trusting the results of an HPT (even though they are quite accurate when taken correctly and at the correct time).
On the other hand, you can go to your health care provider or local clinic to have a urine or blood test done. Some people feel more secure about the results of these tests because the provider’s office is responsible for ensuring that the test is done correctly. Also, if a quantitative test is done, it provides a more specific answer about the “age” of a pregnancy (if there is a pregnancy). A test done at the provider’s office, however, may be more expensive than an HPT. (Some offices and clinics offer free pregnancy tests though, so it may actually turn out to be cheaper.) These tests also require you to make an appointment and go to the office or lab. With blood tests, the results are also typically not available immediately, so you may have to wait a day or more. Another positive of any test done by your health care provider, however, is that there will be someone available to help you and counsel you about your options as soon as they get the results of your pregnancy test. Because you are already in the office, your provider can also help with STI testing, counseling about contraception, and (if necessary) information about your options regarding staying pregnant (if you are planning on either parenting or adoption, you will want to start prenatal care right away) or abortion.
When it comes to taking an HPT versus a test at the health care provider’s office, there is no single right or wrong answer. It is up to you to decide which option is most comfortable and workable for you.
If you choose to take an HPT, you have the additional task of selecting a test. While there is no one “best test” that we can recommend for you, there are several considerations that may help you decide.
- A more expensive test is not necessarily a better test. You do not have to purchase the most costly test you can find. There is no data to indicate that more expensive tests are more accurate than the less expensive tests. The new digital pregnancy tests that are available are more expensive than other tests. While these tests are easy to read, it is not really necessary to pay extra for this. Generally speaking, the more sensitive a test is, the more expensive the test will be. Remember that a more sensitive test is not better, it can simply provide a positive result sooner. If it has been more than 14 days since the sexual activity that could result in pregnancy or if you have missed your period, you probably do not need the most sensitive test available if you would rather not have that cost. The minimum time frame for testing is around 2 weeks from your risk, and if you are testing at this point you may wish to consider a more sensitive test. All tests should have the minimum level of hCG they check for listed on the box.
- A name brand test is not necessarily a better test. A generic or store brand test is capable of providing a result that is just as accurate as a name brand test. In fact, in many cases there is no difference in the actual internal workings of the test. The difference may simply be in the packaging and the price, so do not feel like you have to purchase the name brand.
- Do check the box before you buy. When you select a test, there are two things you want to be looking for on the box. First of all, check the expiration date. Somewhere on the test (usually on one of the ends) there should be a printed or embossed date. If it’s past that date, then you will want to choose a different test. Secondly, look at the overall state of the packaging. If the packaging is open, torn, crushed, or damaged in any way, you don’t want that test. A broken package may indicate that the test inside is in some way damaged as well.
- You may wish to consider purchasing a box that contains two tests rather than just one. HPTs usually come packaged 1, 2, or 3 tests to a box. Obviously, purchasing a box with two tests is going to be more expensive than just one test. However, buying a box with two tests is going to be cheaper than purchasing two single boxed tests. So, if you plan on re-testing to verify your results or if you think you might have need of a pregnancy test later, it might be a good idea to go ahead and buy a multi-test pack now and save the extra test for another time.
- Read the box so you know what you are getting. The box your pregnancy test comes in should have information about the test easily visible. You should know approximately what the test will look like. HPTs come in two basic varieties; one where you urinate directly on the test stick and another where you urinate into a container (which is usually provided for you). The box will also likely show you an example of the type of results window the test has (some tests will show a plus or minus sign, others will show one line or two, or digital tests provide results in words). It should indicate how accurate the test will be when taken at various times and what level of hCG the test checks for. Since many stores are also online, you can also find out a great deal of this information by searching for information about the various brands/types of tests online.
When and how do I use a pregnancy test?
For any pregnancy test, whether it is done at home or at a health care provider’s office, you want to wait a minimum of 14 days from the time of the sexual contact that you're concerned could have resulted in pregnancy or until your period is late. Pregnancy does not occur immediately after intercourse or other unprotected sexual contact. Once a pregnancy does occur, it takes your body some time to produce enough hCG to be detected by a test. So testing any earlier than 14 days after the risk may not provide you with an accurate result. Once you have taken a test, you can verify the results (if you wish) by taking another HPT in about a week if your period has still not appeared or by calling your health care provider for a test around a week from when you took your first test.
Taking an HPT is pretty simple, but surprisingly easy to mess up. When you open the box the test comes in, there should be a sheet of instructions included. Before you open the actual test or do anything else, read all the instructions! In order for a test to provide an accurate result, it must be taken correctly so you’ll want to pay special attention to the instructions. This will tell you when to take the test (whether you can take it at any time or whether you must use first morning’s urine) and how to do it for that test specifically. Do not try to drink lots of extra liquids right before the test in an attempt to increase the amount of urine you produce. This can sometimes dilute the urine to a point where the test might not be accurate. (When in doubt, use first morning's urine since it will be the most concentrated.) Once you’ve established when you should take the test, most instructions will indicate that you should urinate into the toilet for a few seconds before you collect the sample. You’ll then either hold part of the test stick into your stream of urine for a prescribed amount of time or you will use a container to collect some (which you will then dip a test stick into later). The instructions should tell you which part of the test you need to get the urine into contact with. Pay special attention also to how long the test needs to remain in the urine stream or container. If you don’t leave it long enough, you may not collect enough urine to do the test. Leave it in too long and you may skew the results. Next, you will probably be instructed to put the test down on a flat surface (either face up or face down depending on the specific test). After a certain amount of time (usually several minutes), you will be able to read the results based on the instructions for your particular test. Usually tests have two “windows.” The first is a control window which tells you if the test functioned properly. If you do not see a line (or whatever the appropriate indication is on your test) in this window, it means either the test was not taken correctly or it the test was defective in some manner and you will need to try again with a new test. You should also see a “results window” which will indicate the positive or negative result.
Once the appropriate time has passed, throw the test away (and do NOT dig it back out of the trash again). The results of a pregnancy test are only valid for a set amount of time. After that time, sometimes an "evaporation line" can appear in the test window. This is essentially a line that appears as the urine in the test dries, but it does not mean that pregnancy has occurred.
So what do I do after the test?
If your test is negative (and you have taken it correctly and after an appropriate amount of time), you can be fairly sure that you are not pregnant. You can always re-test at any point to verify this or wait for your period to show up. Especially if you have missed more than one period, it would probably be wise to call your health care provider (even if you are receiving negative pregnancy tests). (You can find out more about other things that can cause a period to be late or missed by checking out our article M.I.A or, Dude, Where's My Period?.)
If your test is positive, then you definitely want to see your health care provider as soon as possible. No matter what your plan is for the pregnancy, you will want to make the decisions and seek care as soon as possible. If you plan to continue a pregnancy (either to parent or adoption), you will want to have your pregnancy verified and begin prenatal care as soon as possible. If you plan to terminate a pregnancy, you only have a certain amount of time to do this (see our article All About Abortion for more information).
- Healthwise (2006). Human chorionic gonadotropin (hCG). Retrieved August 17, 2008, from WebMD website: http://www.webmd.com/baby/human-chorionic-gonadotropin-hcg
- U.S. Department of Health and Human Services (2006). Pregnancy tests. Retrieved May 15, 2008, from The National Women’s Health Information Center website: http://www.womenshealth.gov/faq/pregtest.htm
- WebMD (n.d.). Your guide to pregnancy tests. Retrieved May 15, 2008, from WebMD website: http://www.webmd.com/baby/guide/pregnancy-tests