If you are trying to get pregnant or suspect that you might be pregnant, finding out for sure is a top priority. Many home pregnancy tests claim to provide accurate results the earliest, but which of these really lives up to its claim? Learn how home pregnancy tests work, and find out which of these popular brands is most reliable and which ones should be avoided.

How They Work

After conception, it takes several days (usually about six) for the fertilized egg to implant in the uterus. At that point, the mother’s body begins to produce hCG (human chorionic gonadotropin, also known as “the pregnancy hormone”). Home pregnancy tests are treated with special antibodies that react to hCG in the urine. If hCG is detected, the designated line appears. During the first few days after implantation, hCG levels may be as low as 5 to 50 mIU. These levels double every 36 to 48 hours.

Answer Early Result

Answer Early Result tests are a popular choice for women because they are considered to be quite accurate and cost considerably less than other name brands. These tests detect hCG levels as low as 25 mIU, and product packaging suggests accuracy at four days before your period is due. Some women have reported experiencing “disappearing positives” with this brand. These are positive lines that disappear completely and should be considered a negative test result. Strong positive lines that do not fade are considered to be accurate.

Clearblue

Clearblue is another popular home pregnancy test. It features a blue plus or minus sign to confirm or rule out pregnancy. In addition, the urine strip changes color as the urine passes through it to let you know it is working. This test also detects hCG levels of 25 mIU or more, but product packaging suggests that the test can be used four days before the missed period. Tests that use blue dye are notorious for false positives and evaporation lines (a faint line created by evaporation of the urine).

E.P.T.

E.P.T. is the original home pregnancy test. In fact, E.P.T. originally stood for “Early Pregnancy Test.” Today, however, those three letters now stand for “Error Proof Test.” E.P.T. offers both digital and non-digital tests, both of which can detect hCG levels as low as 25 mIU. Anecdotal evidence suggests that false positives may occasionally occur with this test (see Resources). As with any home pregnancy test, a false positive is more likely, particularly when it is taken too early. Product packaging suggest taking the test no earlier than five days before your missed period.

Fact Plus

Fact Plus, like the other early results home pregnancy tests, detects hCG levels of 25 mIU or more. It is recommended, however, to wait until four days before your period is due before testing. Fact Plus tests feature a pink plus sign to indicate pregnancy and a pink minus sign to show a negative result. From an anecdotal standpoint, these tests are considered to be reliable with few false positives reported.

First Response Early Result

The First Response Early Result home pregnancy test is among the most popular on the market. It boasts a clear, easy to read result line and claims to detect pregnancy as early as six days before the missed period. This is the earliest recommended testing time of any available home pregnancy test. Like the other early pregnancy tests, however, the First Response Early Result tests detect hCG levels as low as 25 mIU. False positives have rarely been reported with this brand, particularly since the test was redesigned in 2006.