One of the most frequently asked questions when taking a negative pregnancy test is , is this result reliable? Could it give me a negative result even when I am pregnant?
Before answering this question we must know how a pregnancy test works. Its mechanism is very simple, it consists of the detection in the urine of the hormone called human chorionic gonadotropin ( HCG), which the cells of the placenta begin to secrete at the beginning of pregnancy.
Can the test give me negative and be pregnant?
Keep in mind that urine pregnancy tests will only be positive when there are sufficient levels of HGC hormone in the blood, so at the beginning of pregnancy a test can be negative and yet be pregnant . That is, a false negative .
In general, with a HGC level below 25-50 mIU/mL (milliInternational Units per milliliter of urine), the test will be negative. Therefore, when buying a pregnancy test, you have to look at its sensitivity.
Today , highly sensitive tests are available that detect a concentration of chorionic gonadotropin hormone (CHG), the pregnancy hormone, in urine of 10 to 15 mlU/ml, something that happens between the 7th and 10th day after conception, before notice the lack of menstruation.
As the level increases if the urine is more concentrated, many tests recommend that the first morning urine be tested .
Otherwise, it is enough to wait a few days to perform the test (remember that it is recommended to do the test when there is a delay in menstruation for regular cycles) -or repeat it- so that the levels of pregnancy hormone have increased and are detected by the test.
Reasons for false negatives in the pregnancy test
The reasons why a pregnancy test can be negative even when pregnant are:
- Taking the test too soon : as we have explained before, if the test does not have a sensitivity that is too high, it may still not detect the pregnancy hormone in the blood.
- Do not do it with the first urine in the morning : depending on the sensitivity of the test and how long you have been pregnant, urine from another time of day -more diluted- may not have a sufficient concentration of the pregnancy hormone.
- Doing it wrong – Check each manufacturer’s instructions to make sure you’re doing it correctly. If you have doubts, repeat it.
- Defective or expired pregnancy test : buy it at a reputable pharmacy and check the expiration date on the packaging.
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