How Long To Get A Positive Pregnancy Test

When to Take a Pregnancy Test (Don't Take it Too Early!)

By Lindsay Meisel | Published Aug 16, 2016 | Last updated Jan 13, 2020 ✓ Fact checked
Medically reviewed by Rachel Liberto, RN on August 15, 2019

If you're trying to get pregnant, you've probably experienced the agony of wondering whether you should take a pregnancy test. Especially when you're experiencing potential early signs of pregnancy like nausea, headaches, and fatigue, it can be hard to resist testing early. Do you really need to wait until the first day of your missed period, or can you test earlier?

How long should I wait before taking a pregnancy test?

Pregnancy tests only work when the pregnancy hormone human chorionic gonadotropin (hCG) has built up in your system. This usually happens around 11 – 12 days after ovulation. Most women get their period around 14 days after ovulation.

If you don't know when you ovulated, you can approximate this window by taking a pregnancy test two days before your period is due.

Keep in mind that if you test before your period is due, you may get only a very faint line on the pregnancy test.

How long after ovulation can I take a pregnancy test?

So you're an expert at tracking your ovulation? You may be able to take a pregnancy test earlier. But if you take it before 8 days past ovulation (DPO), you are likely to get a negative test—even if you are truly pregnant.

The reason why has to do with when implantation occurs. While it's technically possible for implantation to occur any time between six and 12 days after ovulation, 85 percent of the time it occurs between eight and 10 DPO, and it only occurs at 6DPO 0.5% of the time. (Our implantation calculator post can help you estimate when it might have occurred for you.)

Even if conception has occurred, the fertilized egg does not start producing hCG—the hormone that pregnancy tests detect—until after implantation is complete. (And speaking of implantation … read our post on the truth about implantation bleeding.)

After implantation, hCG levels start doubling roughly every 48 hours. Baseline hCG levels, early pregnancy hCG levels, and hCG doubling time vary from woman to woman and from pregnancy to pregnancy. Along with the date of implantation, these factors will influence how early you can get a positive pregnancy test.

Deciding when to take a pregnancy test is a risk-benefit calculation: testing earlier than 12 DPO means weighing the risk of being disappointed about a possibly false result against the unlikely outcome of an early positive.

How likely is it to get a false negative pregnancy test?

Most home pregnancy tests are highly accurate if you wait until the first day of your missed period to take it. If you're testing earlier, your chances of a false negative result are higher. The reasons why you might get a false negative include:

Testing too early. Do not test earlier than 12 – 14 days after ovulation. If you don't know when you ovulated, wait until the day your period is due.
Testing too late. If you test after the first few weeks of pregnancy, something called the hook effect can create a false negative pregnancy test.
Testing at the wrong time of day. Test on first morning urine, when the concentration of hCG (the pregnancy hormone) are highest.
Testing on diluted urine. If you drink a large amount of liquid shortly before testing, your urine volume may increase so much that hCG is too dilute to measure (this is more of an issue in early pregnancy, when your hCG levels are still relatively low).
Using a test that is not sensitive enough. If you are testing early, you need to use a more sensitive test (learn more about the best pregnancy tests).
Not testing urine immediately. If the urine collected has been sitting around for too long before testing—usually 30 minutes or more—a false negative result can occur.

Why am I having pregnancy symptoms but a negative test?

There are two possible explanations for this: if your period is late but you have a negative pregnancy test, it most likely means that you ovulated later than usual. The second explanation is that you're taking the test too early, before implantation has occurred.

Should you take a pregnancy test in the morning or night?

If you're testing before your period is due, it's best to take a pregnancy test in the morning, when the concentration of hCG in your urine is highest. If your period is due or late, your hCG levels are likely high enough that you can test any time of day and still get a positive result if you are pregnant.

What are the chances of a false positive pregnancy test?

Truly false positive pregnancy tests are rare. The risk of a false negative pregnancy test is much higher than the risk of a false positive. Below are some possible explanations for false positive pregnancy tests (or, as you'll see, what just seems to be a positive test but actually is not):

Evap or indent line. Waiting longer to read the results than specified in the test instructions can lead to what appears to be a positive pregnancy test, but is actually a result of ink pooling in the body of the test.
LH peak. LH and hCG are biochemically very similar, so the presence of one will test positive for the other. For example, if you are taking ovulation tests and you are pregnant, the LH will be read as hCG (as will LH be read as hCG if you take an ovulation test and you are pregnant).
Sometimes, the hormone hCG can be released from the pituitary at the time of your LH peak. If you take a pregnancy test during this time, there's a small chance of a false positive.
Chemical pregnancy. A high proportion of early pregnancies are miscarried even before the day of your period. Taking a test too early could detect a very early pregnancy that is not viable. Technically, this is not a false positive, because you really were pregnant.
Perimenopause. Perimenopausal women have somewhat elevated levels of circulating hCG, even when they're not pregnant. This could lead to a false positive result.
Infertility treatment. Women undergoing hCG treatment (A.P.L, Pregnyl, Profasi, Pergonal) to stimulate ovulation may also receive false positive results if they test within 10 days of their last injection.

What type of test is best?

If you're testing on the first day of a missed period, it doesn't matter very much which test you use—most currently marketed tests are reliable and will yield a positive result for 98 percent of pregnant women. But if you're testing early, you should use a more sensitive test—just remember that pregnancy tests are less likely to be accurate when taken before your missed period. (Here, we rank the best pregnancy tests by sensitivity.)

The more sensitive the pregnancy test, the more likely it is to detect pregnancy early. But more sensitive pregnancy tests are also more likely to return false positives.

In a study that tested six over-the-counter pregnancy tests, First Response and Answer were the most sensitive. Clear Blue Easy and Walmart Equate tests were the least sensitive.

By Lindsay Meisel | Aug 16, 2016