Receiving a negative pregnancy test often invokes conflicting feelings. While some have a deep sigh of relief, others may tear up in defeat.
In both cases, there is usually a lingering feeling of uncertainty. Taking a second test at a later date is the best way to confirm pregnancy test results.
If a pregnancy test is negative today, can it be positive tomorrow? This is possible. Taking a test too close to conception can yield a negative result even if you are pregnant. This is due to low levels of hCG in the urine until day 10-14 following conception. Since hCG increases rapidly, a positive result could follow a negative result relatively soon after.
Read on to learn more about how pregnancy tests work, how to improve accuracy, and what to know when taking one.
One Day Negative, the Next Day Positive – How & Why
So you’ve taken not one, but two tests, and instead of offering clarity, they gave you mixed results. A negative test followed by a positive test usually indicates a true positive, but why does this happen?
Understanding HCG Levels
Human Chorionic Gonadotropin, otherwise known as hCG, is a hormone produced by the embryonic trophoblast tissue in the developing placenta. These levels help doctors diagnose normal, high-risk, and lost pregnancies.
In early pregnancy, hCG levels double every 72 hours. These levels peak between weeks 8 and 12 and then begin declining as the production of progesterone and estrogen ramp up.
These two hormones will maintain the pregnancy once hCG levels have returned to almost normal.
How HCG Levels Affect Pregnancy Tests
Home pregnancy tests contain antibodies and chemicals that bond to the hCG in urine.
In order for a home pregnancy test to detect hCG in urine, there must be at least 20 mIU/ml. If there is no detectable amount of hCG, the test will yield a negative result.
With non-digital tests, the amount of hCG present in the urine influences the solidity of the second line. Large quantities of hCG will manifest a darker line. This also means that the earlier in pregnancy, the lighter the line will be.
Can a Negative Pregnancy Test Be Wrong?
Yes, a negative pregnancy test can be wrong. False negatives are relatively uncommon and are usually the result of misuse or testing too early.
To avoid a false negative pregnancy test, follow the test directions and wait to test until after the first day of your missed period.
Reasons for False Negative Pregnancy Test
There are many reasons why someone who is truly pregnant could receive a negative result.
Testing Too Early
HCG isn’t detectable in the urine until 10-14 days following conception. For those with a standard 28-day menstrual cycle, this typically aligns with the first few days of a missed period.
Testing before the hCG levels are detectable in the urine could yield a false negative result.
Not Following Directions
Each brand of pregnancy test comes with specific directions to both perform the test and interpret its results. Not following these instructions at any step of the test could cause an inaccurate result.
Reading Test Results Too Early or Late
This is more impactful for non-digital tests, but it applies to all. Reading your test results before they’re fully developed or after they’ve been sitting for a while may lead to inaccurate conclusions.
What Medications Cause False Negative Pregnancy Tests?
As of right now, studies do not irrefutably confirm any medications that are known to cause false negative pregnancy tests, though antihistamines, antidepressants, Parkinson’s medications, certain fertility drugs, and antipsychotics are suspected by some.
If you’re concerned about the accuracy of your pregnancy test due to medications, it’s best to consult your doctor.
What To Do if You Think You Are Pregnant, but the Test Is Negative
Always trust your gut. If you feel as though you are pregnant but the initial test is negative, you should take another test. You can do so by scheduling a blood draw with your doctor, or wait a few days to take another home test.
Accuracy of Pregnancy Tests
Home pregnancy tests are 99% accurate when used according to the directions. False results are rare, and you’re more likely to get a true false negative than a true false positive.
Are Early Detection Pregnancy Tests Accurate?
Yes, these tests are designed differently to detect varying levels and types of hCG. However, accuracy declines the earlier you test.
Generally speaking, they’re 99% accurate from the first day of your missed period and are less accurate every day prior to then.
When To Take Pregnancy Test
If you find yourself having pregnancy symptoms such as nausea, vomiting, tender breasts, and frequent urination, then it’s best to take a pregnancy test.
Additionally, if you’re experiencing things outside of what’s normal for your body during menstruation, you should test for pregnancy.
Pregnancy tests should be taken according to their instructions on the first day after your due period or later.
If you choose to test prior to the first day of your missed period, make sure you select a test designed for early detection. Tests should be taken in the morning, during your first trip to the restroom.
If you’re taking a second test to confirm your results, you should do so 24-72 hours after the first test. Make sure to take this test in the morning as well.
How To Get Accurate Results From Pregnancy Test
If you want the most accurate results, follow the tips below:
- Take the pregnancy test on or after the first day of your missed period.
- Take the pregnancy test during your first urination of the morning.
- Take the pregnancy test according to the manufacturer’s instructions.
- Do not drink excessive amounts of water as it can dilute the hCG.
- Check the pregnancy test expiration date.
- Use a cup of your urine instead of your urine stream.
Can I Take a Pregnancy Test at 4 a.m.?
Yes, you can take a pregnancy test at any time. Taking a pregnancy test at 4 a.m. could be beneficial if it’s following a long period of sleep since your urine will have the highest concentration of hCG.
How Long After Implantation Does HCG Rise?
HCG levels rise from the time of conception until they peak between weeks 8 and 12.
After peaking, hCG levels steadily decline and eventually return to pre-pregnancy levels. At this point, progesterone and estrogen take over in maintaining the pregnancy.
A pregnancy test result can change given time. This means that a negative pregnancy test result isn’t necessarily a true negative, especially if you’re testing early in the menstrual cycle.
Confirming your results should be done via a second home test 24-72 hours following the first or via a blood test with your doctor.
Charley is a mother of three with a passion for raising good humans. With her children in tow, she studies English and has made a career creating content about motherhood. In her free time, she enjoys traveling within the states to kayak, camp, and hike.