How early can I take a home pregnancy test?
An early pregnancy test becomes positive only after the fertilized egg implants in the uterus and then sends enough amounts of hCG, human chorionic gonadotropin, the pregnancy hormone, into your bloodstream, and from there into urine. A urine pregnancy test (home pregnancy test or HPT) checks for the presence of the pregnancy hormone hCG.
A urine pregnancy test is usually not positive until the time of a missed period, about 5-6 days after implantation, while the blood hCG test can be positive a few days earlier than the urine test.
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With most current pregnancy test kits, hCG can be detected in the urine as early as 3-4 days after implantation, though it often takes longer. If you are pregnant, on the day you miss your period about 74% of HPTs will be positive. So a negative pregnancy test is normal in about 26% of all pregnancies, and you may have to retest until you know the most accurate results. At 10+ days after the missed period, a negative HPT result makes pregnancy unlikely. Positive pregnancy test results can show up any time before or after a missed period.
The graph below shows the % of positive urine tests by day if you are pregnant:
The chart below shows the % of positive urine tests by day if you are pregnant:
|Expected Menstrual Period||How often is the
pregnancy test positive?
|3 days before expected period||51% positive|
|2 days before expected period||62% positive|
|1 day before expected period||68% positive|
|Day of expected period||74% positive|
|1 day after expected period||79% positive|
|2 days after expected period||85% positive|
|3 days after expected period||90% positive|
|7+ days after expected period||96% positive|
When is a blood pregnancy test positive?
The blood pregnancy test generally provides greater accuracy earlier. If you are pregnant, your blood test will usually be positive within 3-4 days after implantation or about 9-10 days after fertilization and ovulation, which is roughly 5-6 days before a missed period.
Four factors determine when a home pregnancy test becomes positive
1. Timing of implantation
Detection of hCG depends on the timing of implantation, so hCG can normally be detected in the blood between nine and 16 days after ovulation. Urine hCG can be detected about two to three days after blood hCG can first be seen.
There is a wide normal variation of hCG levels, both in the blood and the urine, and this wide range changes the timing of how early can pregnancy be detected. If a woman has a normal but low blood hCG levels, then it can take several more days for it to show up on a pregnancy test.
Urine hCG levels change over the course of the day depending on how much you drink and how diluted or concentrated the urine. How early pregnancy can be detected depends on the urine concentration and the quality of the early pregnancy test. If you drink a lot of fluid, the urine may be too diluted early on in pregnancy to achieve an hCG concentration adequate enough for a positive test.
4. The sensitivity of the pregnancy test
Different pregnancy tests have different sensitivities and that has an impact on how early can pregnancy be detected. The lower the sensitivity, the earlier a pregnancy test becomes positive. Sensitivities are indicated in mIU/mL, the lowest amount of hCG in the urine that tests positive. A sensitivity of 20 mIU/mL requires one-half the hCG level to be positive when compared with a 40 mIU/mL sensitivity level, and it may become positive several days earlier than the pregnancy test with a higher sensitivity. Make sure you read the package of the pregnancy test to determine your pregnancy test's sensitivity.
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