When a woman believes she's pregnant, it is important to her to be able to trust the results of a pregnancy test. Unfortunately, many women see misleading advertisements that pregnancy tests are over 99 percent effective, which may make her trust a result that she shouldn't. If women learn about the accuracy of pregnancy tests, they will get a better idea of when they can trust the results of a pregnancy test and when they need to retest.
Types
Urine pregnancy tests allow a woman to test in the privacy of her own home or at a clinic. They are about 97 percent effective, according to the American Pregnancy Association. Although a home pregnancy test may claim to be over 99 percent effective, the National Women's Health Information Center explains that this is not always the case. The manufacturers of home pregnancy tests can make these claims if these tests performed that well in laboratory settings, but those results don't always accurately reflect the results in real life.
Blood tests, on the other hand, are done in a doctor's office or clinic. Since medical professionals conduct these tests, they have less room for error and may be more accurate. Quantitative pregnancy blood tests measure the exact amount of pregnancy hormone present in a woman's bloodstream. Qualitative blood tests measure only if the pregnancy hormone is in the blood, but does not provide an exact number of how much or how little of the hormone is present.
Time Frame
Pregnancy tests are typically more accurate the later women take them. For example, taking a test a week before a missed period is less likely to render an accurate result than taking the test a week or more after a missed period. Although many women would like to discover if they are pregnant as soon as possible, it is important to keep in mind that this may affect the accuracy of a test.
False Positives
Fertility drugs, using an expired test or having had a recent miscarriage or abortion are a few things that may skew the accuracy of a pregnancy test to reflect a positive result. Some women also interpret a negative result to be positive when it actually isn't, especially when they see something called an evaporation line. Light lines may appear on the testing strip as urine evaporates. These lines usually appear after the recommend time period for reading the results has passed. Ensuring that all results are read within the manufacturer's recommended time period can decrease the chances of women mistaking an evaporation line for a positive result.
False Negatives
False negative results on a pregnancy test can happen for many reasons. Women who take a test too early or those who had a later-than-expected ovulation or implantation of the fetus may get a negative result when they are actually pregnant. To protect themselves from false negative results, women should pay close attention to the manufacturer's statistics of the accuracy of results before a missed period. For example, even though a pregnancy test may advertise that it can detect results five or six days before a missed period, women who read the package insert may discover only 50 or 60 percent of the women who take a test this early actually get an accurate result. All women who take a pregnancy test before a missed period should consider retesting or contacting her doctor for a blood test in a week or two if her period does not appear or she is unconvinced that the results were accurate.
Warning
Women who use expired pregnancy tests or do not follow the manufacturer's instructions exactly have a higher risk of getting an inaccurate pregnancy test result. Women should take the time to check the expiration date before purchasing the test and make sure to read the instructions thoroughly before taking the test. Women that have questions about how to take the test properly should not feel embarrassed about contacting the manufacturer of the test for advice. Also, the National Women's Health Information Center suggests that taking a home pregnancy test with the first urine of the morning may provide a more accurate result.
