If you think you may be pregnant because you recently had unprotected sex, you missed your period, or you are experiencing other signs and symptoms of pregnancy, you can take a home pregnancy test to find out. These are available at most any drug store and involve testing a small sample of urine for the presence of the pregnancy hormone hCG. However, the results of these tests are not completely reliable. If the amount of hCG in your urine is less than the minimum amount needed for the test to give a positive result, the test will give a “false negative,” meaning it will come up negative even though you are pregnant.

The chances of getting a false negative on a pregnancy test are high in the first week or two after conception. This is because it takes some time for the zygote to begin releasing enough hCG to be detectable on a pregnancy test. Generally, the earliest that one of these tests can come up positive is two to three days prior to a missed period, although a false negative may still occur up to five or six days after a missed period. So, if you take one of these tests and it comes up negative, you may want to take another test a few days or even a week later to confirm the result. If the test comes up positive, you can take another one to be sure. You can also see a doctor to have a blood test that can confirm the pregnancy.