If you think you may be pregnant, taking a pregnancy test as soon as the first day of your missed period can help you get the care and support you need. A home pregnancy test can tell whether you are pregnant with almost 99% accuracy, depending on how you use it. If a pregnancy test says you are pregnant, you should see your doctor for another test to confirm the pregnancy and talk about next steps.
Some home pregnancy tests are more sensitive than others and can be taken before your missed period. But you may get more accurate results if you wait until after the first day of your missed period.
This is because the amount of the pregnancy hormone, called human chorionic gonadotropin, or hCG, in your urine increases with time. The earlier you take the test, the harder it is for the test to detect the hCG.
hCG is made when a fertilized egg implants in the uterus. This usually happens about 10 days after conception (when the man's sperm fertilizes the woman's egg).1
If a home pregnancy test shows that you are pregnant, you should call your doctor to schedule an appointment.
Your doctor can use a blood test to tell for sure whether you are pregnant. Seeing your doctor early in your pregnancy also means you can begin prenatal care to help you and your baby stay healthy.
Yes, it is possible you could still be pregnant. It's possible to be pregnant and to have a pregnancy test show that you are not pregnant.
The accuracy of home pregnancy test results varies from woman to woman because:
If a test says you are not pregnant, take another pregnancy test in a few days. If you are pregnant, your hCG levels should double every 48 hours.1 If you think you are pregnant but more tests say you are not, call your doctor.
Sometimes it can be hard to tell whether the test is positive or negative. The line may be faint, or you may worry whether you peed too much or too little on the stick.
No matter how faint the line or plus sign, if you see it, you are most likely pregnant. The faintness of the line can mean you are early in your pregnancy and your hCG levels are still low.
Also, the pregnancy test should have a control line that tells you whether the test was done correctly. If the control line is blank, then the test did not work and you should take another test.
Pregnancy tests check for the hCG hormone in two ways:
All home pregnancy tests come with written instructions. Depending on the brand you buy, the instructions may vary:
Different brands tell you to wait different amounts of time, although most are around 2 minutes. Depending on the brand of the test, you may see a line or a plus symbol, or the words "pregnant" or "not pregnant." A line or plus symbol, no matter how faint, means the result is positive.
Most tests also have a "control indicator" in the result window. This control line or symbol shows whether the test is working properly. If the control line or symbol does not appear, the test is not working properly.
Look for the toll-free phone number on the package to call in case of questions about use or results.
Most home pregnancy tests claim to be up to 99% accurate. But the accuracy depends on:
Most pregnancy tests claim to be the most accurate after a missed period. But irregular periods can make it hard to predict when to take the test.
Periods are considered irregular if:
If you have irregular periods, try counting 36 days from the start of your last menstrual cycle or four weeks from the time you had sex. At this point, if you are pregnant, your levels of hCG should be high enough to detect the pregnancy.
If your test says you are not pregnant, but you still think you may be pregnant, wait a few more days and take another pregnancy test. Or, call your doctor for a blood test.
Yes. If you take medicine with the pregnancy hormone hCG as an active ingredient, you may get a false-positive test result. A false positive is when a test says you are pregnant when you are not.
Some examples of medicines with hCG include certain medicines for infertility. If you are taking medicine to help you get pregnant, you may want to see your doctor for a pregnancy test.
Most medicines should not affect the results of a home pregnancy test. This includes over-the-counter and prescription medicines such as birth control and antibiotics. Also, alcohol and illegal drugs do not affect pregnancy test results.
All pregnancy tests work by detecting the pregnancy hormone, hCG, in the urine or blood. This hormone is present only when a woman is pregnant. If the pregnancy test detects hCG, it will say you are pregnant.
hCG is made when a fertilized egg implants in the uterus. This usually happens about 10 days after conception (when the man's sperm fertilizes the woman's egg).1 The amount of hCG builds up quickly in your body with each passing day you are pregnant.
So if you take a home pregnancy test too soon after implantation, your hCG level may not be high enough to detect the pregnancy. If the test says you are not pregnant, take another pregnancy test in a few days.
For more information about pregnancy tests, call the OWH Helpline at 800-994-9662 or contact the following organizations:
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Page last updated: February 17, 2017.
Content last reviewed: April 27, 2014.