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What Causes An Invalid Pregnancy Test

what is invalid pregnancy test

A positive or negative result on a pregnancy test can bring about a whirlwind of emotions and decisions for those trying to conceive or those concerned about unplanned pregnancies.

In this comprehensive article, we examine the various factors that can lead to an invalid pregnancy test result, offering insight into the reasons behind this occurrence and suggesting what to do if it happens to you.

Women checking Invalid Pregnancy Test
invalid pregnancy test

Understanding pregnancy Test:

A pregnancy test detects the presence of human chorionic gonadotropin (hCG), a hormone produced by the placenta during pregnancy, in a woman’s urine. These tests work by using antibodies to hCG to produce a visible line or symbol on the test strip, indicating whether a woman is pregnant or not. When hCG levels rise in the body, it signals the early stages of pregnancy.

A positive result suggests that hCG is present in sufficient quantities to confirm pregnancy, while a negative result indicates its absence. Pregnancy tests are valuable tools for individuals seeking to confirm pregnancy, but they are most accurate when used following the test’s instructions and during the recommended testing window, typically after a missed period.

What is an Invalid Pregnancy Test?

A negative pregnancy test result indicates that the test was either unable to detect or reject the presence of a pregnancy hormone in your urine, known as Human Chorionic Gonadotropin (HCG).

Main Causes of Invalid Pregnancy Test

Invalid pregnancy test results can be caused by many factors. As a health care provider I am going to mention some of the common factors below!

  • Too early pregnancy test
  • Inappropriate Practise 
  • Expired kits
  • Dilute Urine
  • Medication
  • Ectopic pregnancy 
  • Chemical pregnancy 

Too Early Pregnancy Tests

Testing too early can lead to invalid pregnancy results because hormone level did not rise at that time

  • Low HCG levels: HCG levels are usually very low during the first few weeks of pregnancy. The body begins to make hCG after the fertilized egg has been implanted in the uterus. This usually happens about 6 to 12 days after fertilization. HCG levels are too low before implantation to produce a positive pregnancy test result.
  • Sensitivity Threshold: The sensitivity threshold of a pregnancy test is the minimum amount of human chorionic gonadotropin (hCG) that the test can detect. Some tests have a higher sensitivity and are able to detect lower hCG levels, whereas others require a higher hCG concentration to produce a positive result.
  • False negatives: Testing too soon, especially before a period break, can lead to false positives as the hCG levels have not yet reached the test sensitivity level.

Inappropriate Practice

Inappropriate practices during the pregnancy test can lead to invalid results due to errors in the testing process.

  • Insufficient urine sample: Insufficient urine sample neither soaks the test strip properly nor react HCG leading to invalid results. 
  • Timing error: Pregnancy tests have specific time windows in which results should be read. Leaving the test unattended for too long or reading the result too soon can lead to inaccuracies.

Not Following Test Instructions: Failing to follow the manufacturer’s instructions carefully, including the steps for collecting urine, timing, and result interpretation, can lead to errors and invalid results.

Expired Kits

Using expired kits can lead to faulty results. You should check the expiry date before buying a pregnancy kit. Expired or damaged kits can lead to false results due to these reasons:

  • Reduced sensitivity
  • Chemical breakdown
  • Inaccurate control lines

Diluted Urine

The dilution of hCG in urine is caused by overconsumption of water and frequent urination. This is also the most common reason for negative test results. To get accurate results, you must use early morning first urine as it is less dilute.


1. Fertility Medications: Some fertility medications contain human chorionic gonadotropin (hCG) or hCG-like substances. When a woman takes these medications, her body may produce hCG, which can be detected by a pregnancy test. Depending on the timing and dosage of these medications, they can lead to false-positive results on a pregnancy test, as the test may detect the hCG from the medication rather than a pregnancy.

2. Hormonal Birth Control: Hormonal birth control methods, such as birth control pills, patches, or injections, contain synthetic hormones that can affect the menstrual cycle and hormone levels. While these methods do not contain hCG, they can lead to irregular periods or hormonal fluctuations that might cause a woman to suspect pregnancy. Testing during this time could produce inaccurate results.

3. Other Medications: Some medications can interfere with the accuracy of pregnancy tests. For example, medications that affect hormone levels or metabolism may indirectly impact hCG production or clearance from the body, potentially leading to false results. 

4. Diagnostic Procedures: In some cases, medical procedures or diagnostic tests that use contrast agents or substances that affect the body’s physiology may lead to temporary changes in hormone levels. These changes could impact the reliability of a pregnancy test if performed shortly after such procedures.

Health Conditions

Pregnancy test results may be inaccurate due to certain underlying health conditions that affect hormone levels and the menstrual cycle. Some of the health conditions that affect pregnancy test results include:

  • Polycystic Ovary Syndrome (PCOS): PCOS is a hormonal disorder that can lead to irregular menstrual cycles and elevated levels of certain hormones, including luteinizing hormone (LH). Elevated LH levels can sometimes be mistaken for a surge in human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests. This confusion can result in false-positive or invalid pregnancy test results.
  • Ectopic pregnancy: When an egg implants outside of your uterus, usually in your fallopian tube, it can cause you to have lower levels of human chorionic gonadotropin (hCG). So, if you think you’re pregnant but a pregnancy test says you’re pregnant, you might be wrong.

Chemical pregnancy

A chemical pregnancy, also known as a biochemical pregnancy, is a very early pregnancy loss that occurs shortly after conception, often before a woman even realizes she is pregnant. 

It involves a brief rise in hCG (human chorionic gonadotropin) levels followed by a rapid decline which leads to confusion and shows invalid results.

How Do You Avoid a Pregnancy Test Error?

You need to follow all the instructions properly to avoid any kind of error in the pregnancy test.

Follow Instructions

Carefully read and understand the instructions provided with the pregnancy test kit. Different brands may have specific guidelines, so it’s crucial to follow them precisely.

  • Collect urine samples for pregnancy tests in the morning just because it is highly saturated and HCG level is high.
  • Avoid drinking excessive fluids before testing because it will dilute the urine leading to low HCG level.

Wait after Missed Periods

Wait until after your expected period date to test for pregnancy. Testing too early can lead to false negatives. This is because it allows more time for the hormone hCG, which the test detects, to reach detectable levels in the body.

Check the Expiry Date

Always check the expiration date on the pregnancy test kit. Using an expired kit can yield unreliable results. Throw away expired kits and use new ones for accurate results.

Minimize External Contaminants:

Keep the test area clean and avoid contact with contaminants, such as dirt, dust, or lotion, that might affect the test.

Be Mindful of Medications:

Be aware of any medications or fertility treatments you are taking, as they can potentially interfere with pregnancy test results. Consult with a healthcare provider if you have concerns.

If you receive unexpected or unclear results, consult with a healthcare provider for further evaluation. A blood test can provide a more accurate pregnancy assessment.

false positive vs. invalid pregnancy test

False Positive vs. Invalid Pregnancy Test

It’s important to know the difference between a false positive test and a pregnancy test that is invalid. A false positive test means the test shows a pregnancy when there isn’t one, usually due to medication or medical issues. An invalid test shows a testing error, usually due to inadequate urine or a faulty test kit, and requires a retest to get a reliable result. It is important to follow test instructions closely and to seek medical advice if you get unexpected or unclear results.

How Long to Wait Before Retaking a Pregnancy Test After an Invalid Result

It is common practice to retest a pregnancy test after getting an invalid result. The amount of time you should wait varies depending on the type and brand of test you use, so it is important to review the test instructions. However, the general rule of thumb is to wait at least 48 to 72 hours after getting an invalid test result. During this time, it is important to carefully follow your test instructions to ensure you get accurate results on your retest. If you get an invalid test result on your second test or if you still have questions about your pregnancy, talk to your healthcare provider for more information and advice.

Why it is Important to Consult with a Healthcare Provider After an Invalid Result

Consulting with a healthcare provider after receiving an invalid result on a pregnancy test is crucial for various reasons. Healthcare professionals can offer more accurate pregnancy confirmation through blood tests that detect lower levels of hCG, reducing the risk of false results. 

Additionally, they can assess your overall health, rule out underlying issues affecting fertility, and provide guidance on the best timing for testing. Emotional support and resources for coping with pregnancy-related stress are also available from healthcare providers.

 For those trying to conceive, discussing potential treatments and family planning options becomes possible. Furthermore, a thorough health assessment can identify factors influencing conception and pregnancy, ensuring comprehensive care for reproductive and emotional well-being.


In conclusion, an invalid pregnancy test result can arise due to various factors such as testing errors, inadequate samples, expired kits, or certain medications. To avoid this, it’s crucial to follow test instructions carefully, use the right timing and urine, and be aware of potential contaminants. If an invalid result occurs, waiting for 48 to 72 hours before retesting is advised, following proper procedures. For persistent issues or concerns, consulting a healthcare provider is recommended. Understanding these factors ensures more accurate and reliable pregnancy testing, reducing stress and uncertainty in the process.


Certainly! Here are some frequently asked questions (FAQs) related to the article on invalid pregnancy tests:

1. Can a pregnancy test be invalid if it shows a faint line?

  • A faint line on a pregnancy test can be a valid positive result if it meets the test’s criteria for positivity. However, if the line is very faint and difficult to interpret, it may be advisable to retest to obtain a clearer result.

2. Is an invalid pregnancy test the same as a negative result?

  • No, an invalid pregnancy test is different from a negative result. A negative result indicates that the test did not detect pregnancy, whereas an invalid result means that the test cannot provide a clear outcome due to testing errors or other factors.

3. How can I avoid getting an invalid pregnancy test result?

  • To avoid an invalid pregnancy test result, it is important to carefully follow the test’s instructions, use the first morning’s urine for testing, check the test kit’s expiration date, and minimize potential contaminants during testing.

4. When should I consider retesting after receiving an invalid result?

  •  If you receive an invalid pregnancy test result, it is generally recommended to wait at least 48 to 72 hours before retesting. However, you should refer to the specific test’s instructions for accurate guidance.

5. What should I do if I continue to receive invalid test results?

  • If you consistently receive invalid pregnancy test results or have concerns about pregnancy, it is advisable to consult with a healthcare provider. They can conduct more accurate tests and provide guidance.

6. Can certain medications or medical conditions affect pregnancy test results and make them invalid?

  • Yes, certain medications and medical conditions can potentially interfere with pregnancy test results and lead to invalid outcomes. It’s essential to be aware of these factors when taking a pregnancy test.

These FAQs provide useful information for individuals who may encounter issues with pregnancy test results and are seeking clarification on the topic of invalid pregnancy tests.

Read Also: What Does a Blank Pregnancy Test Mean?

Rose Smith
Rose Smith Writer, Pregnancy guide specialist Expertise Rose Smith is a dedicated and experienced writer, specializing in the field of Nursing and pregnancy guidelines. With a strong educational foundation, extensive experience, and a passion for supporting expectant parents, Rose has become a go-to source for reliable pregnancy advice and information. Experience Rose Smith's professional journey is marked by a wealth of experience: Authorship: Rose has authored numerous articles, essays, and books on pregnancy guidelines, all backed by her academic knowledge and practical insights. Pregnancy Workshops: She has conducted workshops and seminars, both online and in-person, providing expectant parents with practical tools and advice. Consulting: Rose has worked as a pregnancy consultant, offering personalized guidance to expectant mothers and couples. Media Contributions: Her expertise has been featured in various publications, including parenting magazines and health websites. Education Rose Smith holds a Master's degree in Nursing from Oxford University, where she laid the foundation for her expertise in maternal health, prenatal care, and pregnancy-related topics. Additional Certifications Certified Nurse-Midwife (CNM) Doula Certification: Doulas, who provide emotional and physical support during pregnancy and childbirth, often seek certification through organizations like DONA International. Childbirth Educator Certification. University Specialties As a proud alumna of Oxford University, Rose's areas of specialization include: Maternal Health: Her academic background has equipped her with a deep understanding of the physical and emotional aspects of pregnancy and maternal well-being. Prenatal Care: Rose's education focused on the importance of proper prenatal care and its impact on a healthy pregnancy. Nutrition and Pregnancy: She has in-depth knowledge of nutrition during pregnancy and its role in fetal development.

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