Can A Pregnancy Test Be Wrong?

image001Many women find themselves upset by the results of a pregnancy test and this can be in cases where they want to be pregnant as well as those in which they do not want to be. Can a pregnancy test be wrong? 

If you are upset by the results of your pregnancy test it is important to keep in mind which factors can affect it. Many women, for example, will take a pregnancy test before the first day of a missed menstrual cycle and receive an incorrect reading. Learn about all the causes of false pregnancy test so that you could make a better judgment.

Can A Pregnancy Test Be Wrong?

The results of pregnancy tests may not always state correctly whether or not you are pregnant, that is to say, pregnancy test could be wrong. False negative tests are more common than false positive. 

Although a pregnancy test may give a false positive or false negative, this does not make it wrong in the technical sense. That is because a positive result will depend on your personal pregnancy. It takes a week or more for the fertilized egg to reach the uterine wall and become implanted after ovulation. Even after this occurs, it may be another few days before the body begins producing enough hCG, the pregnancy hormone, to be detected. Some women feel certain that they know when they ovulate but even in this case, ovulation may vary, leading to false reading on a pregnancy test. In fact, a difference of even a day in your ovulation can lead to lower hCG levels and therefore a false negative result.

You will notice that many home pregnancy tests make the claim of being 99% accurate on the first day of a missed period. Research suggests that they aren’t consistent at detecting pregnancy at this stage but they are reliable when you wait until a week after your missed period and follow the instructions carefully.

False Positive Pregnancy Test

Most home pregnancy tests are between 97% and 99% accurate but despite this, it is still possible to receive a false positive. Home pregnancy tests work by detecting your level of hCG (the pregnancy hormone human chorionic gonadotropin). Although all women naturally have a low amount of this hormone in their urine (and blood), the amount increases exponentially after the embryo is implanted into the uterine wall and it is the resulting high levels that pregnancy tests detect. Because the tests are based on hormone readings, it is possible to get a false positive for several reasons.

1. Chemical Pregnancy—Early Miscarriage

A chemical pregnancy is the term used to describe a miscarriage that occurs very early on in the pregnancy. In this case, the pregnancy test was correct in determining that you successfully conceived but the miscarriage occurred early enough where your menstrual cycle still arrived on time. In fact, some experts believe that among the miscarriages, many of them are chemical pregnancies. Most women who have a chemical pregnancy don’t even notice unless they are actively trying to conceive.

2. Effects of hCG Trigger Shots

If you are trying to conceive, your fertility specialist may give you an hCG shot which will stimulate ovulation. It does by rupturing the follicle that carries the egg and therefore encouraging ovulation. This can lead to false positive readings if the extra hCG hasn’t completely left your system yet. For accurate results, be sure to wait 14 days to test for pregnancy if you had a 10,000 IU injection, ten days for a 5,000 IU injection or seven days for a 2,500 IU injection.

3. Evaporation Line

When using a home pregnancy test, you should always read the results within a specific time frame that is usually about five minutes. If you wait too long, you may confuse urine evaporation lines with a positive test line that is faint. These evaporation lines appear as the urine dries, making it important to read the result soon after taking the test.

4. Improper Testing

Each home pregnancy test will have specific instructions including how long to wait before reading the test. It is crucial to always follow these instructions exactly as some tests can produce a faint positive if you wait too long to read the results. Always use a timer or clock to measure the amount of time since performing the test instead of simply guessing.

5. Use of Certain Medications

There are certain medications that can interfere with the results of home pregnancy tests including hCG therapy (as mentioned above). Medications containing phenothiazine can also cause false readings as can urine that is contaminated with large amounts of protein or with blood.

6. Medical Conditions

Although rare, certain medical conditions may lead to a false positive on your pregnancy test. Choriocarcinoma and other forms of cancer including testicular, ovarian, or breast cancers may lead to elevated hCG levels and a false positive.

7. Defective Pregnancy Test

It is always possible for you to have purchased a defective pregnancy test although this is extremely rare. In addition, tests become less accurate if they are expired, so always check the expiration date before using your pregnancy test.

False Negative Pregnancy Test

Although false positive results tend to be more common than false negatives, it is possible for you to have a false negative on your pregnancy test. If you had a negative result on your pregnancy test and feel like you might be pregnant, consider if one of the following situations applies. These are the main reasons that you could have a false negative.

1. Testing Too Early

As mentioned earlier, pregnancy tests rely on the quantity of hCG in your urine to determine whether you have conceived. The placenta will start secreting this hormone immediately after implantation but that doesn’t take place until seven to ten days after ovulation. After that the hCG levels will double every 48 to 72 hours but still won’t reach the levels necessary to be detected by a home test until six or seven days after ovulation.

2. Low Sensitivity of Pregnancy Test

Another possible reason for a false negative is if the sensitivity of your home pregnancy test is too low. Some tests are highly sensitive and can detect as little as 20mIU/mL but many only detect a much higher quantity. If you are testing for your pregnancy soon after ovulation (such as seven days after), then it is possible that a test that only detects levels of 100mIU/mL will not detect your pregnancy. A more sensitive one set for 50mIU/mL or less, however, will probably detect it in this case.

3. Diluted Urine

When you urinate frequently or drink a lot of water you can decrease the detectable quantity of hCG in your urine. This is why you should always test right away in the morning as your hCG levels will be most concentrated at this time. Instead of doing a pregnancy test later on in the day, it is better to wait until the next morning for more accurate results.

4. Missed Reaction Time

Just as reading your pregnancy test too late may give you a false positive, this or even reading it too early can give you a false negative as well. Because inaccurate readings are associated with reading the pregnancy test too early or too late, you should always keep a timer on hand.

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