When to Take a Pregnancy Test

How hCG rises

Home tests look for human chorionic gonadotropin (hCG). Your body does not make meaningful amounts until the fertilized egg implants in the uterus, which happens roughly 6 to 10 days after conception. Only then does hCG start to climb.

Once it begins, hCG roughly doubles every two days or so in early pregnancy. That doubling is why a day or two of patience makes a real difference: a level too low to detect today can be clearly positive a couple of days later. For many tests, hCG becomes detectable in urine around 10 days after conception, which lines up closely with the first day of a missed period.

Implantation timing also varies. In up to about 1 in 10 people it happens after the day the period was due, which means hCG starts later and a test on the expected day can still read negative even in a real pregnancy. That single fact explains most early false negatives, and it is the reason a second test a few days later is worth doing.

Test accuracy by timing

Earlier testing detects fewer pregnancies. Confirm a negative by retesting if your period has not come.

When you test	What is happening with hCG	Reliability
Before a missed period (early-detection test)	hCG may be too low or not yet present	Low; high chance of a false negative
First day of missed period	hCG detectable for most pregnancies	High; the recommended time to test
1-2 days after missed period	hCG has continued to roughly double	Higher; catches later implanters
About a week after missed period	hCG well established if pregnant	Highest; clearest result

How to test for the most reliable result

Small steps that protect accuracy.

• Use first-morning urine when you can, because it is most concentrated and contains the most hCG.
• Check the expiration date and follow the package timing exactly.
• Read the result inside the stated window, usually within a few minutes, and not after it.
• Treat any line in the result area, even a faint one, as a positive.
• If you tested early and got a negative, retest on or after the day your period was due.

Faint lines and false negatives

A faint line usually means you are pregnant, just early, with a low hCG level, or you are using a test with naturally light lines. It still counts as positive. Do not confuse it with an evaporation line, which can appear if you read the test long after the time window has passed, so always read on time.

False negatives almost always come from testing too early, before hCG has built up. They can also come from technique, such as using too much or too little urine or diluted urine late in the day. If your period does not arrive and the test is negative, wait two to three days and test again. A negative test plus a missed period is a reason to check in with your doctor.

Reflects Cleveland Clinic and MedlinePlus guidance on home pregnancy testing and hCG, 2024-2026.

Related questions

Can I take a pregnancy test before my missed period?

You can, but accuracy drops sharply because hCG may be too low to detect. Up to about 1 in 10 people implant after the first day of the expected period, so an early negative is unreliable. For confidence, test on or after the day your period is due.

Why is first-morning urine recommended?

It is the most concentrated urine of the day, so it holds the most hCG and gives the clearest early result. Later in the day, fluids dilute your urine and can lower a borderline reading. If you test later, try not to drink large amounts beforehand.

Does a faint line mean I am pregnant?

Usually yes. A faint line typically reflects a real but low hCG level, common very early in pregnancy. Confirm it by retesting in two to three days, when hCG should be higher and the line darker, or with a blood test.

How accurate are home pregnancy tests?

Used correctly after a missed period, they are about 99% accurate, matching the accuracy of tests done in a clinic. Most errors come from testing too early or not following the instructions. A blood test can confirm a result when needed.

Sources & further reading

1. Cleveland Clinic — Pregnancy Test: When To Take, Types & Accuracy
2. MedlinePlus — HCG (urine) pregnancy test
3. Cleveland Clinic — Am I Pregnant? Early Pregnancy Symptoms & When To Test

This article reflects current AAP, CDC, FDA, and other public-health guidance and is for educational purposes only. It does not constitute medical advice. ParentFlow is a wellness companion — not a substitute for your pediatrician. For any medical concern, contact your healthcare provider.