Pregnancy tests detect the human chorionic gonadotropin hormone, or HCG, which is produced after a fertilized egg implants itself into the lining of the uterus. Early pregnancy tests are able to detect lower amounts of this hormone, sometimes as little as 25 or even 12.5 mIU (international units). Tests are considered reliable when the results are easy to read and do not contain false results or evaporation lines, which may appear as the tests begins to dry and can be mistaken for a positive result.
First Response Early Result
Touted by many women as the most reliable early test available, First Response Early Result tests have a published sensitivity rating of 25 mIU. Independent laboratory testing, however, has found that these tests may be as sensitive as 12.5 mIU. First Response tests are found to be reliable with fewer errors and a decreased likelihood of evaporation lines. False positives rarely occur on these tests. Due to the increased sensitivity of this test, it is possible to detect a pregnancy that would otherwise have been undetected due to an early miscarriage occurring before the expected period occurred.
Answer Quick and Simple Early
This test has a reported sensitivity of 25 mIU with easy-to-read lines that makes interpreting the results of the test less of a challenge. These tests have few reports of evaporation lines or errors, a reliable choice for women who want to test earlier but don't want to worry about ambiguous results. Answer tests are also less expensive than many others, starting at $9.99 in drugstores and grocery stores nationwide.
Clearblue Easy Digital Easy Read
Testing with a digital test is the easiest type of test to use and interpret because instead of reading lines, the results are displayed simply as "pregnant" or "not pregnant." Many digital tests have a lower sensitivity, eliminating their usefulness as an early result test. Clearblue Easy Digital Easy Read, however, boasts a sensitivity as low as 25 mIU, allowing women to test earlier than their expected period with accurate results as early as 8 to 10 days after ovulation in some cases. As with any pregnancy test, testing too early may produce a false negative result if the fertilized egg has not yet implanted. Always retest after a few days if a negative result is received.
