False Negative Pregnancy Test Calculator
Calculate the probability of a false negative pregnancy test result based on timing and test characteristics
Calculate False Negative Probability
Number of days since your expected period date
Lower values detect pregnancy earlier
Morning urine has highest HCG concentration
Average length of your menstrual cycle
False Negative Test Analysis
Test result is highly reliable
Recommendations
- •Wait at least 1 week after missed period for most accurate results
Medical Disclaimer
This calculator provides estimates only and should not replace professional medical advice. If you suspect pregnancy or have concerns about test results, consult with a healthcare provider for proper evaluation and blood testing. Ectopic pregnancies and other complications require immediate medical attention.
Test Sensitivity Guide
HCG Level Timeline
3-4 weeks: 5-426 mIU/ml
Early detection possible
4-5 weeks: 18-7,340 mIU/ml
Most tests accurate
5-6 weeks: 1,080-56,500 mIU/ml
Highly reliable results
Testing Tips
Use first morning urine for highest accuracy
Wait at least 1 week after missed period
Check test expiration date
Follow test instructions exactly
Retest if symptoms persist with negative result
Understanding False Negative Pregnancy Tests
What is a False Negative?
A false negative pregnancy test occurs when you are actually pregnant, but the test shows a negative result. This happens when the level of human chorionic gonadotropin (hCG) in your urine is too low for the test to detect.
Common Causes
- •Testing too early (before hCG levels rise sufficiently)
- •Using diluted urine (not first morning urine)
- •Low-sensitivity test that can't detect low hCG levels
- •Ectopic pregnancy (abnormal implantation)
- •Expired or faulty test
HCG and Pregnancy Detection
Human chorionic gonadotropin (hCG) is produced by the placenta after implantation. Levels typically double every 48-72 hours in early pregnancy, but can vary significantly between individuals.
When to Retest
- •If tested before missed period, wait 1 week and retest
- •If pregnancy symptoms persist with negative test
- •After 3-5 days if initial test was negative
- •Consider blood test for definitive results
Important Note About Ectopic Pregnancy
Ectopic pregnancies can produce lower hCG levels and may result in false negative tests. If you have risk factors for ectopic pregnancy (history of PID, tubal surgery, previous ectopic) or experience severe abdominal pain, seek immediate medical attention regardless of test results.