Home Pregnancy Test FAQs

Since its introduction in 1977, the home pregnancy test has been the easiest and most private way to find out if you are pregnant. The test kits are inexpensive and can be purchased without a prescription at any drug store. Extremely dependable when used correctly, many home pregnancy tests can tell you if you are pregnant as soon as the first day of your missed period.

What is hCG?
HCG stands for human chorionic gonadotropin, a hormone secreted by the cells that will become the placenta. Shortly after the embryo attaches to the wall of your uterus, your hCG levels will increase rapidly and continue to double every 2 to 3 days until they reach their peak around weeks 8-11 of your pregnancy. Home pregnancy tests are designed to detect hCG in your urine.

Why does the hCG level of the test matter?
Not all home pregnancy tests are the same. The tests that detect the lowest concentration of hCG (in milli-International Units per milliliter of urine) are more sensitive to hCG and will give you the earliest reliable results. For example, tests that can detect 20 mIU/ml are more sensitive than those that can detect 50 to 100 mIU/ml.

How do home pregnancy tests work?
Home pregnancy tests are designed to detect hCG, a hormone secreted by the developing placenta soon after fertilization. If you are pregnant, the hormone is present in your urine and in your blood.

How accurate are home pregnancy tests on the first day of a missed period?
The accuracy of a home pregnancy test always depends on when you take it and how well you follow the instructions and interpret the results. In ideal conditions, home pregnancy tests are an estimated 90 percent accurate when taken on the same day you miss your period. If you take a home pregnancy test one week after the first day of your missed period, however, accuracy increases to an estimated 97 percent.

How soon after ovulation can I test?
The earliest you can get an accurate result on the most sensitive pregnancy tests is seven days after ovulation. The hCG hormone is produced only after implantation, which generally happens 6 to 12 days post ovulation, so you should wait at least 10 days after ovulating to take a home pregnancy test to decrease the chance of getting a false negative.

How long do I need to hold my urine before taking a home pregnancy test? Because home pregnancy tests detect hCG, it is best to collect urine containing the highest amount of the hormone. Diluted urine, caused by drinking a lot of fluids, can lower the test's accuracy. Waiting at least 5 hours after going to the bathroom before taking a home pregnancy test is sufficient, but your first morning urine is considered the best because it contains the most concentrated presence of hCG.

How do I take a home pregnancy test?
Before you take the test, make sure it hasn't expired! If it has, throw it away and get a new one. Read the instructions carefully before you start, as they vary among different brands. Most home pregnancy tests require you to either urinate in a cup or directly onto a stick, while others give you the choice. For the most accurate results, you should use your midstream urine, meaning you should pee a little first before you hold the test stick in your urine stream. When you're finished, place the stick on a clean, dry surface and wait for your results. Processing times range anywhere from 1 to 5 minutes, depending on the brand of your test.

How do I read the test result?
Be sure to read the instructions for your home pregnancy test carefully, as different tests display their results differently. Most of them have two windows, one that tells you if you've done the test correctly, and one that tells you if you are pregnant or not. Make sure you read the results when your test's instructions tell you to. If the test detects hCG, a positive sign will appear in the result window, which may be represented by a line, dot or symbol. Even if the line is faint, you should consider it a positive result. To confirm a questionable result, try taking another test a few days later when your hCG levels may have increased.

Which is more accurate, a urine test or a blood test?
Blood tests are slightly more sensitive than urine tests because they can detect very low levels of hCG. This means they can provide a more accurate result within about 7-12 days after conception. There are two types of blood tests doctors use to test for pregnancy. A quantitative blood test measures the exact amount of hCG in your blood, which makes it quite accurate. Qualitative hCG blood tests just check to see if the pregnancy hormone is present or not, giving you a simple yes or no. The qualitative hCG blood test is about as accurate as a urine test.

Are urine tests at the doctor's office any more sensitive than home tests? Doctors usually use the most sensitive pregnancy tests, able to read hCG levels as low as 15 to 25mIU/ml. They are basically the same as the most sensitive tests you can buy over-the-counter.

Is it possible to get a false positive result?
False positive test results are uncommon, but they do happen. Conditions which could lead to a false positive include letting the test sit for too long, or having had infertility treatments in which you may have received fertility drugs containing the hCG hormone. If you are not sure about your test results, you should try again after a couple of days. If you still have doubts about the test's accuracy, schedule an appointment with your doctor for a blood test.

If the result is negative, can I still be pregnant?
Yes. Home pregnancy tests are not 100 percent accurate. If you still think you might be pregnant even after a home pregnancy test gives you a negative result, you should see your doctor for a quantitative hCG test.

What if I took a test and the result was negative, but when I looked at it an hour or more later I saw a faint line?
You may be pregnant, but your level of hCG was too low for the test to detect it in the usual time frame. But a late-forming line does not necessarily mean you are pregnant. Sometimes evaporation lines can form if a home pregnancy test is left to sit for awhile. In either case, the best thing to do is take another test in a few days.

Can I use a home pregnancy test if I had an hCG injection (such as Profasi, Pregnyl or Novarel)?
You can, but you should wait 7 to 14 days to make sure the hormone is out of your system. Testing too soon could result in a false positive as a result of the hCG in your blood as a result of the injection.

Can fertility medications such as Clomid, Serophene, Gonal-F, Follistim, Humegon, Pergonal, Repronex or Fertinex cause false positives on home pregnancy tests?
The only fertility drugs that can cause a false positive are those that contain hCG.

Can progesterone supplements cause a false positive home pregnancy test?
No. Home pregnancy tests are designed to detect hCG, not progesterone. They are two completely different hormones.

Can I tell if my hCG level is doubling by retesting with a home pregnancy test and looking for a darker line? No. Home pregnancy tests are not accurate enough to show an increase in your hCG level. Only a quantitative blood test can show you this.

What if my hCG levels aren't doubling every 2 to 3 days from a quantitative blood test?
Don't worry, it doesn't necessarily mean something is wrong. Still, your doctor will want to perform an early ultrasound because slow-rising hCG can be related to impending miscarriage or ectopic pregnancy. On average, hCG levels double every two days from 4 to 6 weeks, then every three days, and finally slowing to every four days. Levels peak near the end of the first trimester, and it isn't until the second trimester that hCG levels start to decline.

If I am pregnant, how long will my doctor monitor hCG levels?
Doctors usually do two or three hCG levels to confirm that yours is doubling. Because hCG levels vary, many doctors will stop monitoring after the baby's heartbeat is detected. Once a heartbeat is seen or heard, the chance of miscarriage drops significantly.

I had a positive result, but my period started. What happened?
It could have been one of two things: a false positive, or an early miscarriage. The only way to know for sure is to ask your doctor immediately for a quantitative hCG blood test. If you were pregnant and had an early miscarriage, the test can still detect the hormone in your system on the first day of bleeding.

I got a negative test result last week but I still haven't started my period. Should I test again?
Yes. Most home pregnancy test instructions state that you should take another test if you haven't started your period a week after you received a negative result. The test may not have picked up the hCG in your system.

I have all the symptoms of a pregnancy and got a faint positive on a home pregnancy test. My qualitative (yes/no) hCG blood test came back negative. Am I pregnant or not?
Be sure you're checking the results of your home pregnancy test in the time specified by the instructions to ensure you are not seeing an evaporation line. The best thing to do is have a quantitative hCG blood test done to measure your actual hCG level.

Can prescription or over-the-counter medication interfere with home pregnancy test results?
No. Unless the medication contains hCG, it will not interfere with your test result. The same goes for over-the-counter medicine like pain relievers and cough suppressants.

Do oral contraceptives/birth control pills interfere with home pregnancy test results?
No, your result should be accurate. The hormones in the Pill do not cause a false positive or false negative result.

Will recreational drugs or alcohol interfere with home pregnancy test results?
No, but you should not take a home pregnancy test while under the influence of alcohol or recreational drugs, as it may increase your chance of error.

Can a urinary tract infection cause a false positive result?
No. Home pregnancy tests are designed to detect the hormone hCG. Byproducts of infection will not interfere with your results, but you should have them confirmed by a doctor. Also be sure to have the UTI treated as soon as possible!

Can stress cause a false positive result?
No.

How much does a home pregnancy test cost?
Most drugstores sell home pregnancy tests for anywhere from $8 to $20, depending on the brand and how many tests come in the box.

Which brand of home pregnancy test is the best?
In 2003, Consumer Reports ranked home pregnancy tests based on their efficacy, ease of use and ease of result readings. First Response Early Result Pregnancy Test came out on top as the most reliable and sensitive test, earning an "Excellent" rating overall. If you'd like to use a different brand and are unsure of which to choose, ask a doctor or pharmacist.