Home Pregnancy Tests – How to Use a Popular Test Wisely
The first home pregnancy tests were marketed in the mid 1970’s. These tests are one of the most popular products for home diagnostic testing. It is estimated that about 33% of women have used these tests. The tests are popular because they allow women rapid access to highly sensitive and personal information. These tests can lead to earlier diagnosis and can provide pregnant women an opportunity to seek earlier health care intervention.
FDA is involved in the premarket review of these tests. Since the 1976 Medical Device Amendment, FDA assures that new pregnancy tests perform as well as those tests on the market since 1976. Premarket compares test performance between a new test and an established test. In these kinds of pregnancy devices the new test is compared to varying levels of the hormone human chorionic gonadotropin (hCG) that is the marker for pregnancy.
Recent investigators point out that the FDA review of analytical performance does not always mean a woman is pregnant. This discrepancy is because different tests have different abilities to detect low levels of hCG. Also hCG levels differ between pregnant women depending on the timing of the onset of pregnancy with regard to a menstrual period and depending on each woman’s unique biology.
The result is that pregnancy tests may be labeled up to 99% accurate when compared to other hCG tests, not to pregnancy. This may be true based on information submitted to the FDA. Therefore, labeling of these tests should clearly indicate that there is a possibility for both false positive tests and false negative tests, so patients should contact their health care provider to discuss any result.
Patients may frequently recognize incorrect results with the passage of time. False negatives may be detected by ongoing failure to have a period or the development of other obvious signs of pregnancy. False positives may be demonstrated by the unexpected onset of menses (regular vaginal bleeding associated with “periods”.) Repeat testing and/or other investigations such as ultrasound may provide corrected results.
If a patient has a negative result, it is always wise to consider this a tentative finding. Women should not use medications and should consider avoiding potentially harmful behaviors, such as smoking or drinking alcohol, until they have greater certainty that they are not pregnant.
Since September of 2003, studies for pregnancy tests have been posted on the Office of In Vitro Diagnostic Web Page under new 510(k)s – decision summaries. FDA is considering what educational or regulatory tools might be available to help clarify the status, use, and interpretation of these tests.