How Early Can You Detect Pregnancy?

Pregnancy can be detected as early as three to four days after attachment to the uterus. Before this time pregnancy tests may come back with negative results.

An early pregnancy test will only provide accurate results after a fertilized egg has been implanted in the uterus. Once this happens, the egg starts sending a hormone called human chorionic gonadotropin, or hCG, into the bloodstream. Women may start to experience the first physical signs of pregnancy at this point since the production of hCG triggers hormone activity. The hCG hormone is also called the pregnancy hormone, as it is only produced once a woman becomes pregnant. There are several tests women can do to determine whether or not they are pregnant. Tests can be done either by a urine sample or a blood test. Each has a different method of testing for pregnancy, but urine and blood samples both measure the same hormone. Pregnancy tests can be performed either at home or at a physician's office.

Urine Pregnancy Test
Depending on the test, it may take some time for women to find out whether or not they are pregnant. A urine pregnancy tests checks for pregnancy by measuring hCG in the urine. In general, it takes about nine days for a urine test to come up with positive results from a pregnancy. This is due to the fact that the implanting blastocyst takes several days to start producing hCG levels in the bloodstream. Blood hCG levels generally surge after implantation and peak for about seven to 10 days before they start to decline.

The urine test can be performed in one of two ways, according to The first method involves taking a urine sample in a cup and then either putting a stick into the urine or taking a sample with an eyedropper. The alternative method is using a stick to collect a urine sample during the process of urination. Tests differ in the amount of time it takes to get the results back, but they will show a positive pregnancy in the same way. Women should watch for a change in color or a line on the stick. Some tests may indicate pregnancy with either a positive or negative symbol on the stick. Urine tests done at home and the doctor's office have an accuracy level of about 97 percent, according to Women should be aware, however, that doing the tests too soon or inaccurately can affect the test results.

Blood Pregnancy Test
Blood tests are also used to determine whether or not a woman is pregnant. There are two types of blood tests. The quantitative blood test looks for the precise amount of hCG in a woman's bloodstream. In contrast, the qualitative hCG blood test simply provides an affirmative or negative answer to whether or not a woman is pregnant. The advantages of a blood test are that blood tests can detect pregnancy about a week to 12 days sooner than a urine test can, and blood tests can be more accurate as they measure the concentration of hCG in a woman's bloodstream, which in turn indicates the likelihood of a pregnancy. The disadvantages of blood tests are that they must be done at a doctor's office, and that it can take longer to get the results back. Blood tests can also be more expensive than urine tests.