Positive pregnancy test one day and negative the next

For many women, gathering up the courage to take a home pregnancy test is one of the most stressful experiences ever. There is nothing more devastating than to take a test one day and have a positive result only to take a second test the following day and get a negative result. Since home pregnancy tests are 97% accurate, the question about whether or not the individual is in fact pregnant is a valid one.

Chemical Pregnancies and Early Miscarriages

One of the most common reasons for a positive result one day followed by a negative result the following day is due to a chemical pregnancy, which is commonly known as an early miscarriage.

According to Baby Centre, early miscarriages are miscarriages that occur within the first trimester of pregnancy and is predicted that as many as 25% of all pregnancies end in a miscarriage. Early miscarriages are an extremely common occurrence and may explain why historically, there has been a tradition of not announcing a pending birth until after the first trimester.

The signs of an early miscarriage are simply heavier periods and some women can go through their cycle without a clue that they have miscarried.

Overly Sensitive Pregnancy Tests

Home pregnancy tests work by testing a woman’s Human Chorionic Gonadotropin or hCG levels. This hormone is one of the first to increase during pregnancy. Many women who have been trying to get pregnant for a long period of time have access to high-end technology and testing methods which are able to pick up the slightest increase in the level of the hormone.

If you are testing shortly after conception, the level of hCG in your system will be very low. Testing at different times of the day or drinking too much liquid before testing can produce a negative pregnancy test result when the hCG levels are extremely low.

False Negative Pregnancy Test

Another reason why the second test may have a negative result is that the home pregnancy test may have been faulty and not worked properly. While this is not typically the case, it can occur on rare occasions.

Instead of taking a pregnancy test as soon as possible, it is better to wait until your cycle has run its course. Waiting until a period has been missed is much more accurate than taking a pregnancy test shortly after conception.

Hi everyone,

Netmums moderator here, just dropping in to add a link to some official information...

Sadly, one possible explanation for a positive pregnancy test followed by many negative pregnancy tests, is an early miscarriage - also known as a 'chemical pregnancy'. According to Tommy's:

"Sometimes women have a positive blood test or pregnancy test, but [...] a pregnancy test may be negative after just a few days."

Learn more and get support here: https://www.tommys.org/baby-loss-support/miscarriage-information-and-support/types-of-miscarriage/chemical-pregnancy-information-and-support

There is another possibility, but it's much less common. According to Healthline "One explanation for a false negative pregnancy test is what’s called the hook effect. It’s not common but sometimes this effect leads to urine and blood tests giving the wrong result. This error might happen even after you’ve had one positive pregnancy test and test again a couple days later".

This can happen if you have "too much" of the pregnancy hormone hCG in your system. It's more likely in multiple pregnancies, and can sadly also be a sign of a molar pregnancy. If you have any concerns, or experience pregnancy symptoms, nausea, pelvic pain or vaginal bleeding, see your GP as soon as possible.

Learn more here: https://www.healthline.com/health/pregnancy/hook-effect#pregnancy-tests

Or check out our article on what the faint line on your pregnancy test really means: https://www.netmums.com/pregnancy/what-the-faint-line-on-your-pregnancy-test-really-means

After getting a negative result on a home pregnancy test, it's fair to conclude that you're not pregnant. However, if you happen to glance back at the test later in the day, you may be surprised to see that a positive line has magically appeared. There are a few reasons why this can happen. However, in most cases, the originally reading of the test, "not pregnant," is typically the correct one.

What Are Evaporation Lines on a Pregnancy Test?

The instructions on most pregnancy tests will advise you to read the results within a certain window of time. This usually ranges between a couple of minutes up until 10 minutes later. If you see a positive result beyond this time frame, you may be left second-guessing the results.

However, the false-positive reading, in this case, is due to something called an evaporation line. Evaporation lines are not indicative of a true positive result.

Evaporation lines happen when the urine that was on the test area starts to dry. The chemical composition of the urine sample changes due to evaporation. As a result, the test may start to display a positive line. After the allotted time has passed, you should discard the pregnancy test to avoid confusion.

What Do Faint Pregnancy Test Lines Mean?

If you follow all of the instructions correctly, you may notice a thin, faint test line that appears within a few minutes. It can seem at first that the line is too faint to count, but after 10 minutes, it darkens. There are several possible explanations for this line:

• Chemical pregnancy: When implantation of a fertilized egg happens, hCG is produced, even though that egg may not be viable. Chemical pregnancies are the most common cause of early miscarriage. Without taking a pregnancy test, the miscarriage may easily be mistaken for a regular period.
• Lower sensitivity test:You might need a test with higher sensitivity levels so that you can get accurate results earlier in the pregnancy. Look for "early results" indicated on the test label.
• Too early in your cycle: If you test earlier than 10 to 12 days past ovulation, the hCG hormone may not be high enough to produce more than a very faint line. The best time to test is after your period is late, or 2 weeks after you ovulated.
• Too much fluid: You can dilute your urine sample if you are urinating too frequently or drinking too many liquids—this is why first-morning urine samples are recommended for pregnancy testing.

False Negative Results

While true false negative results are rare, there are multiple reasons why you could get a negative or faint result even if you are actually pregnant, such as not waiting long enough into your cycle to test or testing with diluted urine. Always use a sample from your first-morning urine (which is more likely to have higher concentrations of the pregnancy hormone, hCG).

If you are still unsure about pregnancy test results, wait a few days and test again. If you have any questions or concerns about whether or not you could be pregnant, consult with an OB/GYN.

A Word From Verywell

It can very stressful to see conflicting results on a pregnancy test, such as faint lines or evaporation lines. If you're unsure about your results, retest in a couple of days or talk to your doctor about a follow-up blood test for confirmation. Following the directions on your pregnancy test helps avoid the confusion or disappointment of a false positive.

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Robin Elise Weiss, PhD, MPH
Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.

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