Pregnancy tests are generally very accurate, with most home pregnancy tests claiming about 98% to 99% accuracy when used exactly as instructed

. However, they can sometimes be wrong due to various factors.

How Often Are Pregnancy Tests Wrong?

• False Negatives (Test says not pregnant but you are):
  False negatives are more common than false positives. They mainly happen if you test too early, before the pregnancy hormone hCG has risen enough to be detected, or if the test is not used properly (e.g., improper urine amount or timing)

. Research shows false-negative rates can be as high as about 5% or even up to 24% in some studies, especially if testing is done less than 9 days after a missed period

. False negatives can also occur several weeks into pregnancy due to test limitations or hormone fluctuations

• False Positives (Test says pregnant but you are not):
  False positives are rare but can occur. Causes include:

  • Recent pregnancy loss (miscarriage, chemical pregnancy)
  • Fertility drugs containing hCG
  • Certain medical conditions like ovarian cysts, kidney disease, or hormone disorders
  • Reading the test result after the recommended time, causing evaporation lines to appear as false positives

Summary

Type of Error| Frequency| Common Causes
---|---|---
False Negative| Up to ~5-24%| Testing too early, improper use, hormone levels
False Positive| Very rare (<1%)| Recent pregnancy loss, fertility meds, medical conditions, test misuse

If a test is negative but pregnancy is still suspected, it is advised to retest a few days later or consult a healthcare provider. Positive results are generally reliable but should also be confirmed with a healthcare provider, especially if fertility treatments or medical conditions are involved

. In conclusion, pregnancy tests are very accurate when used correctly, but false negatives are more common than false positives, particularly when testing is done too early or incorrectly.