How to Confirm Pregnancy After a Missed Period
Perform a urine pregnancy test immediately when you miss your period, understanding that most FDA-approved tests can detect pregnancy before the first missed menses in normal intrauterine pregnancy, though 10% of pregnancies may not be detectable on the first day of the missed period due to delayed implantation. 1, 2
Immediate Testing Approach
Use a home urine pregnancy test as your first step:
- Most FDA-approved qualitative urine pregnancy tests have a sensitivity of 20-25 mIU/mL for human chorionic gonadotropin (hCG) 1
- These tests can yield positive results before the first missed menses in most normal intrauterine pregnancies 1
- With current test kits (sensitivity 25 units per liter), urine may reveal positive results 3-4 days after implantation, and by 7 days after the expected period, 98% will be positive 3
Understanding Test Limitations
Be aware that timing significantly affects accuracy:
- Up to 10% of clinical pregnancies have not yet implanted by the first day of the missed period, making them undetectable even with extremely sensitive assays 2
- The maximum screening sensitivity on the first day of the missed period is estimated at 90% (95% CI, 84%-94%) 2
- By 1 week after the first day of the missed period, screening sensitivity increases to 97% (95% CI, 94%-99%) 2
- An additional 11 days past the day of expected menses may be needed to detect 100% of pregnancies using qualitative tests 1
When to Seek Medical Evaluation
Contact a healthcare provider for pregnancy testing if you have:
- Missed menses (unless using etonorgestrel implants or depot medroxyprogesterone acetate) 1
- Irregular bleeding (unless using etonorgestrel implants or depot medroxyprogesterone acetate) 1
- New onset pelvic pain 1
- Enlarged uterus or adnexal mass on examination 1
Important Clinical Considerations
Understand that pregnancy tests cannot detect:
- Pregnancy resulting from recent sexual intercourse (tests require time for hCG to rise to detectable levels) 1
- Very early pregnancies before implantation has occurred 2
Be aware of false results:
- Pregnancy tests may remain positive for several weeks after delivery or abortion (spontaneous or induced) because hCG can persist in the body 1
- With current generation test kits using monoclonal antibodies to beta-hCG, false positive results due to interfering materials are extremely unlikely 3
- Home pregnancy tests vary widely in their ability to detect different forms of hCG, with 60% of devices having poorer detection limits for hyperglycosylated hCG (the principal form in early pregnancy urine) compared to regular hCG 4
Follow-Up Testing
If the initial test is negative but pregnancy is still suspected:
- Repeat the urine pregnancy test in 2-4 weeks 1
- A negative result 1 week after the missed period virtually guarantees that you are not pregnant 3
- Consider blood testing through a healthcare provider for earlier or more sensitive detection if clinically indicated 1
Critical Pitfall to Avoid
Do not assume all home pregnancy tests are equally accurate despite similar packaging claims - studies show that many home pregnancy test results do not match the claims made in package inserts, and there are currently no standard criteria for testing performance despite all being CE-labeled 5