Pregnancy tests: hCG sensitivity explained

Summary

Home pregnancy tests detect human chorionic gonadotropin (hCG) in urine. Sensitivity varies by brand and timing. Testing too early or with dilute urine increases false negatives.

Key points

• Many tests claim detection from ~10–25 mIU/mL hCG, but real-world sensitivity depends on urine concentration.
• First-morning urine is often most concentrated.
• A false negative is more common when testing before a missed period.
• False positives are rare but can occur with certain medications, recent pregnancy loss, or rare tumors—follow up with a clinician.

What research suggests

CDC guidance recommends following test instructions and repeating testing after a missed period if symptoms persist. Blood hCG quantification in clinical labs is more sensitive than most home tests.

Limitations

Test lines are not a diagnosis. Ectopic pregnancy and miscarriage require medical evaluation even after a positive test.

References

• CDC — Pregnancy testing
• FDA — Home use tests: pregnancy