Have you just received a negative pregnancy test and still have no period? There are 5 possible reasons for a false negative pregnancy test. You could still be pregnant, or something else might be happening.
Whatever the case is, a home pregnancy test can show a false negative or a false positive. Getting to know the causes of false-negative pregnancy tests would help you understand what is going on.
It is important to keep in mind that you should take a home pregnancy test correctly and at the right time in order to get the highest possible accurate result. If you want to know the 5 possible reasons for a false-negative pregnancy test, keep reading.
In this post, I will discuss the following.
- Are home pregnancy tests accurate?
- Can a negative pregnancy result be false?
- Can a positive result be wrong?
- Possible Reasons for a False Negative Pregnancy Test
- How common is it for a pregnancy test to be a false negative?
- What are some reasons your period is late besides pregnancy?
- What to do if you get a negative and have no period?
This post is for informational purposes only and should not be taken as medical advice. This post may contain affiliate links. I may earn a small commission if you purchase something.
Are home pregnancy tests accurate?
Most pregnancy tests if taken correctly and at the right time are highly accurate. However, there are different types of home pregnancy tests, and they all differ in accuracy.
Even though most pregnancy tests are considered to be 99 percent accurate, first response pregnancy tests are the most sensitive pregnancy tests and can detect early pregnancy and an HCG level of 5 Miu/ml.
You should take a pregnancy test a day after you miss your period. HCG levels at that time would be high enough for the pregnancy test to detest the HCG, the pregnancy hormone.
You need to know how to take a pregnancy test to avoid a false negative. For most at-home pregnancy tests, you need to dip the test into a cup of urine for a few seconds. Then, you should wait 3 to 5 minutes for the result. The result would appear as a symbol like a smiley face or a sad face, or a line like two lines or one line, or as words like pregnant, non-pregnant, positive, or negative.
Below is a chart showing how accurate pregnancy tests are at each DPO.
|# of DPO
|Accuracy of Pregnancy Test
Reasons for a false negative blood pregnancy test?
Can a negative pregnancy result be wrong?
Yes, there are many causes for a false-negative pregnancy test. Getting the wrong negative pregnancy test is not very common and is usually due to mistakes the tester commits. That is why if you think you are pregnant and get a negative result, you should see a doctor to confirm the results.
Can a positive result be wrong?
Yes, a positive pregnancy test result can be wrong or false. It is rare, but it could happen. You may get a false positive if you still have HCG in your system after a miscarriage, have a molar pregnancy, or are having a chemical pregnancy.
You could also get evaporation lines. Evaporation lines are faint lines on a pregnancy test that do not indicate pregnancy. The dried-up urine makes this colorless, faint line.
Medications can cause false-negative pregnancy tests. There are also drugs that cause false positive pregnancy tests. Many fertility drugs contain HCG, the pregnancy hormone. It takes time for the HCG to leave the body. If you are in the process of IVF, the trigger shot is one of the causes of false-positive pregnancy tests. Some more medications that affect pregnancy tests include benzodiazepines, phenothiazine, and promethazine.
You could get a false positive from the following:
- You were exposed to heterophile antibodies.
- You got a blood transfusion
- Taking hCG for weight loss or fertility can cause a false-positive.
- IgA deficiency can also cause a false positive.
- Certain cancers can cause a false positive pregnancy test.
Possible Reasons for a False Negative Pregnancy Test
There are five possible reasons for a false negative pregnancy test, and they include using the pregnancy test incorrectly, taking the pregnancy test early, miscalculating your cycle, using diluted urine, and the hook effect.
You could get a false negative blood test too. False pregnancy tests happen by:
Using the Pregnancy Test Incorrectly
You could get a false negative result by taking a pregnancy test wrongly. You must follow the directions that are found in the pregnancy test box. Also, you must wait the recommended time before reading the result. Each pregnancy test has a certain list of directions for using the pregnancy in the correct way. Always read the instructions.
Taking the Pregnancy Test Early
To get accurate results, you must not take a pregnancy test too early. The best results are achieved one day after you miss your period. Before then HCG levels are too low to be detected unless you use a very sensitive pregnancy test. yo
After the egg is fertilized, it moves down the fallopian tubes into the uterus and attaches itself to the uterine wall. Only then does the embryo begin to release HCG.
This usually occurs between 5 DPO and 12 DPO. So, if you test during these days, your HCG levels may be too low to be detected by a pregnancy test.
The earliest you can get a positive on a pregnancy test is at 6 days past ovulation.
You miscalculated your menstrual cycle.
If you miscalculate what day you are on in your cycle, you may not know when you have ovulated and may take the pregnancy test too early. This is one of the things that can cause false negative pregnancy test.
Remember, you must be at least 6 DPO to get a positive on a pregnancy test, and the majority of women don’t even get a positive until 9 DPO.
You can use ovulation tests to determine when you ovulate. This is the best method to use when trying to calculate how many days past ovulation you are. It is also a great way to avoid false negatives.
You used diluted urine (low HCG levels).
You must use concentrated urine when using a pregnancy test. If you use diluted urine, the HCG levels would be too low for the pregnancy test to detect it.
That is why it is recommended to use first-morning pee for pregnancy tests. First-morning urine is very concentrated. If you forget to use morning urine, you can try to hold your urine for three hours and then test.
Hormonal imbalances like the hook effect can cause false negative pregnancy tests. The hook effect occurs when there is too much HCG in the urine or blood. The test is overwhelmed by the high levels of HCG and gives out a false-negative result. That is because the antibodies the pregnancy test uses to detect pregnancy cannot combine with the HCG hormone. The hook effect is very rare. It unfortunately can occur in both a pregnancy blood test and a urine pregnancy test.
In addition, many people also have asked:
- Can blood in urine cause a false negative pregnancy test?
The answer is no. Blood in the urine does not affect pregnancy tests.
- Can fibroids cause false negative pregnancy tests?
No, fibroids do not release any hormones. So, they do not affect pregnancy tests.
Reasons for False-Negative Blood Test
A blood pregnancy test can give false negatives too for a few reasons. Some causes for a false-negative pregnancy blood test are:
- Chemical Pregnancies
- Ectopic Pregnancies
- Certain Cancers
- The Hook Effect
How common is it for a pregnancy test to be a false negative?
Getting a false negative pregnancy test is not very common. It actually happens 5 percent of the time. To avoid getting a false negative, I recommend using first-morning urine after you miss your period. The best time to test would be 15 DPO. The chance of getting an accurate result on an at-home pregnancy test is quite high.
What should I do if I get a negative result and have no period?
- You should consult with a doctor to find out any issues you may have. The following are some problems that may stop your period from coming.
- Thyroid Dysfunction
- High Prolactin
- Overweight and Underweight
- High stress or exercise