How early to get a positive pregnancy test

Pregnancy tests work by detecting the presence of a hormone called human chorionic gonadotropin (hCG) in your urine. Some home pregnancy tests claim they're sensitive enough to give a positive result as early as five days before you would expect your next period. But you're more likely to get an accurate result (and avoid a false negative pregnancy test) if you wait to test until after the first day of your missed period.

How soon can you take a pregnancy test?

You're more likely to get an accurate result if you wait a few days to a week after you expect your period before taking a pregnancy test.

Some home pregnancy tests claim they're sensitive enough to give you a positive result as early as five days before you would expect your next period. And some women will have produced enough hCG to get a positive result at that point. So if you're anxious to know, go ahead and try it. If you get a negative result, you can just wait and test again later if you still haven't gotten your period.

Most home pregnancy tests claim to be accurate on the day you miss your period, but even then, the amount of hCG in the urine at this time can vary a great deal from one woman to another.

If you test too soon, you may get a false negative pregnancy test (a negative result even if you are pregnant) or an unclear result like a faint line on a pregnancy test.

How do pregnancy tests work?

Home pregnancy tests tell if you're pregnant or not by detecting the presence of hCG in your urine.

This hormone is produced by cells that will develop into the placenta. It first enters your bloodstream when the fertilized egg starts to implant in the lining of your uterus, as early as six days after fertilization.

The amount of hCG in your body then increases rapidly over the next few weeks, often doubling every two days or so. When a pregnancy test detects the hormone in your urine, it shows a positive result.

Home pregnancy tests are now about 99 percent accurate, when done correctly. And there's no reason to pay more for one test over another. As long as a test isn't expired, it should be equally as accurate as another test.

What will differ between tests is their sensitivity. Detecting hCG in the urine of someone 6 months pregnant (when there's plenty of hCG) versus 6 days past ovulation (when there's a very small amount of hCG) are two very different tasks. The ability of a test to pick up small amounts of hCG in your urine depends on the sensitivity of the test.

It's not always easy to tell which tests are the most sensitive. New products come out frequently, and manufacturers can make improvements at any time.

But some package inserts provide information about a test's sensitivity – that is, they report the lowest concentration of hCG in milli-International Units per milliliter (mIU/ml) of urine that the test can detect. For example, a pregnancy test that claims to be able to detect hCG at 20 mIU/ml should be more sensitive than one that claims to detect it at 50 mIU/ml.

How do I use a home pregnancy test?

For best results when using a home pregnancy test:

• Make sure the test is current. Check the expiration date on the package, especially if you've had it for a while. If you've been storing the test anywhere that gets moist or warm, like the bathroom, it may have deteriorated. If that's the case, it's better to throw it away and get a new one.
• Test first thing in the morning. Your urine is most concentrated when you first get up, so hCG levels (if present) will be easier to detect at that time.
• Read the directions carefully. Directions vary with different brands. Some require you to urinate in a cup and then use the dropper provided to place a small sample in the testing well. With others, you can pee directly onto the testing device. And some let you do either.

The tests also vary in how they display the results. For example, some show pink or blue lines on the test strip, while others reveal a red plus or minus sign in a window. "Digital" tests tell you in words whether you're pregnant. Most have a control indicator (often a second line or symbol) to indicate whether the test is valid.

It may take up to 10 minutes to see results. If the control indicator doesn't show up properly, the test may be faulty. If this happens, you can usually call the manufacturer and have them send you a new one (though it probably won't arrive soon enough to use that same month).

If you have questions about how to use a test, call the manufacturer's toll-free number on the package instructions.

If the test shows a negative or a faintly positive result, wait another few days or a week and try again if you still haven't gotten your period. One possibility is that you ovulated later in your cycle than you thought and took the test too early to get a positive result.

Don't assume that one negative result means you're not pregnant. The amount of hCG produced is different for every woman and varies with each pregnancy. If you suspect that you're pregnant (for instance, if you're having early pregnancy symptoms) and still have a negative test, repeat a urine pregnancy test in a week if you still haven't gotten your period.

If you still haven't gotten either your period or a positive result two weeks or so after you would expect it, contact your healthcare provider.

False positive pregnancy tests

A false positive pregnancy test means that you get a positive result, but aren't pregnant. These are uncommon, but they can happen under certain circumstances:

• You had a miscarriage or a pregnancy termination in the previous eight weeks or have a molar pregnancy.
• You've taken a fertility drug containing hCG (used to induce ovulation in fertility treatments).
• You have a rare medical condition, such as an hCG-secreting tumor.
• You're using an expired or faulty test.
• You're experiencing menopause or perimenopause.

If you have an early positive result and then get your period soon after, you may have had what's sometimes called a chemical pregnancy. This means a fertilized egg implanted in your uterus and developed just enough to start producing hCG, but then stopped developing for some reason. This form of early pregnancy loss usually happens when the fertilized egg has defects that prevent it from growing normally.

After a chemical pregnancy, your period may be a little heavier and a few days later than usual.

Note: An ectopic pregnancy usually results in a positive pregnancy test, even though these pregnancies show slower hCG rises. No matter what result you get from a pregnancy test, call your healthcare provider right away if you:

• Feel dizzy or faint.
• Have abdominal pain (especially a sharp or stabbing pain in your abdomen or on one side of your pelvis).
• Have abnormal bleeding.

Pregnancy blood tests

Most healthcare providers use a urine pregnancy test, just as you would at home – but your provider may use a blood test instead. It takes anywhere from an hour to a day or more to get the results.

There are two types of pregnancy blood tests:

• A qualitative hCG blood test simply detects whether there is hCG in your blood. It will give pregnancy results at about the same time as a urine test. The results return as "positive" or "negative."
• A quantitative blood test (beta hCG test or serum test) measures the exact amount of hCG in your blood. The results return as a number. This test is very accurate. It can detect hCG as early as six to eight days after ovulation, about a week before your period is due. It takes longer to get results from a quantitative blood test, though.

Some testing companies will let you pay online and then go to a lab and have a blood sample taken. The testing company will provide you with your result the next day by phone or online. These tests start at about $40. If you decide to use one of these companies rather than going through your healthcare provider, be sure to find out which type of blood test they're using.

What to do after a positive pregnancy test

Some women take more than one pregnancy test (or several) just to be sure – but that's not necessary. Once you've gotten a positive pregnancy test, call your healthcare provider to set up a prenatal visit or to discuss your options if you're uncertain about continuing the pregnancy.

For prenatal care, providers typically schedule the visit for when you're at least 8 weeks pregnant, but it varies. Some will see you sooner, particularly if you have a medical condition or have had problems with a pregnancy in the past. It's especially important to see a provider soon if you're having nausea and vomiting, vaginal bleeding, or abdominal pain.

If you don't already have a family doctor, ob-gyn, or midwife, do some research and ask for recommendations. But don't delay your care while searching for a good fit, because you can always switch providers later. At your first prenatal visit, your provider will take your health history, explain your options, and more.

Learn more:

• I'm pregnant – now what?
• Implantation bleeding
• Pregnancy symptoms

How soon will a pregnancy test read positive?

Can you detect a pregnancy at 1 week?