What can cause a weak positive on a pregnancy test?

Although modern home pregnancy tests appear to be fairly easy to read, confusion can result if a mild or mildly positive result appears. A mild positive pregnancy test result is most likely to occur on tests that show a color change reading or the appearance of lines to indicate pregnancy. There are a variety of reasons why a mild positive can occur. In most cases, a second test or a visit to a medical professional will confirm actual results.

Pregnancy tests measure a hormone in the urine that appears when women become pregnant. The sensitivity of the test and the duration of the pregnancy can affect the result. If a test is done earlier than recommended, the test may not be able to detect the small amounts of hormones present. It may also be easier to get a weak positive if the test is not a very sensitive version and only measures high volumes of the pregnancy hormone.

User error is a common cause of a weak positive on a pregnancy test. Testing too soon, not following the instructions exactly, using an expired or damaged test, or reading the results after a longer period of time than stated may cause a faint line or color change. Be sure to read all instructions exactly before using the test and check the expiration date. If necessary, set a timer to ensure the results are read at the right time. Keep pregnancy tests stored in a cool, dry area, as excessive heat or humidity can cause the test to malfunction.

Certain hormonal imbalances can cause a mild positive on a pregnancy test. Women who take certain medications or take fertility-enhancing drugs can easily end up with a false result. Occasionally, women undergo what is known as a chemical or hysterical pregnancy, where the body produces signs and hormones of pregnancy, even without a pregnancy present. In these cases, it is best to visit a medical professional for additional tests that can confirm or refute a pregnancy.

If a mild positive occurs, some experts recommend waiting a few days and retesting. Since first morning urine is the most concentrated, it may be easier to get a clear result then. Also, the amount of pregnancy hormones doubles every few days in a pregnant woman, so a weak positive can quickly turn into a clear positive after a short wait.

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