When to Take a Pregnancy Test
For most accurate results, take a pregnancy test 1 week after your missed period, as this timing virtually guarantees accurate detection of pregnancy. 1, 2
Optimal Timing for Pregnancy Testing
Earliest Possible Testing
- 7-10 days after conception: Serum hCG tests can detect pregnancy this early 3
- 3-4 days after implantation: Urine pregnancy tests may show positive results (approximately 10-14 days after conception) 3
- First day of missed period: 90% of pregnancies can be detected, but 10% of clinical pregnancies remain undetectable at this point 4
- One week after missed period: 97-98% accuracy in detecting pregnancy 2, 4
Testing Based on Specific Situations
Take a pregnancy test in these circumstances 1:
- Missed menstrual period (unless using etonorgestrel implants or depot medroxyprogesterone acetate)
- Irregular bleeding
- New onset of irregular bleeding after prolonged amenorrhea while using hormonal contraception
- New onset pelvic pain
- Enlarged uterus or adnexal mass on examination
- Before starting new medications with potential adverse effects for pregnant women or fetuses
Understanding Pregnancy Test Sensitivity
- Most FDA-approved qualitative pregnancy tests have a sensitivity of 20-25 mIU/mL in urine 1
- Test sensitivity affects detection rates relative to timing of missed menses 1
- Some studies show an additional 11 days past expected menses may be needed to detect 100% of pregnancies using qualitative tests 1
Factors Affecting Test Accuracy
- Recent sexual intercourse: Tests cannot detect pregnancy immediately after intercourse 1
- Recent pregnancy termination: hCG can remain present for several weeks after delivery or abortion 1
- Test brand differences: First Response tests (both manual and digital) detect 97% of pregnancies on the day of missed period, while other brands may detect only 54-67% 5
Test Selection
- For earliest detection: Use serum hCG testing 7-10 days after conception 3
- For reliable urine testing: Wait until the first day of missed period 3
- For near-certain results: Test urine 1 week after missed period 3, 2
Important Considerations
- A negative result one week after missed period virtually guarantees the woman is not pregnant 2
- Serial measurements provide more valuable information about pregnancy viability than isolated readings 3
- In viable pregnancies, hCG should increase by at least 53% over 48 hours in early pregnancy 3
- False positive results with current generation test kits are extremely unlikely 2
Early pregnancy detection is crucial for avoiding potentially harmful medications, radiation exposure, or treatments that could affect the developing fetus 6. When in doubt, consult with a healthcare provider who can perform more sensitive serum testing if needed.