Pregnancy test: false negatives
Can you be pregnant if the pregnancy test is negative? How reliable is the result of home tests and in which cases can they be wrong?
Taking a pregnancy test can be a nerve-wracking experience, whether you’re trying to have a baby or desperately hoping you’re not pregnant. Stress can be even greater if you are unsure of the outcome .
In this article, we’ll look at whether it’s possible for a negative pregnancy test to be wrong, what the potential causes are, and what to do to minimize the risk of an error.
Can a negative pregnancy test be wrong?
Urine tests available on the market today have an accuracy of 99%. This means that the test itself is extremely reliable .
However, it may happen that the result is negative even in the presence of a pregnancy : in this case we speak of a false negative .
When can this happen?
A pregnancy test can give a false negative when:
- it is done too soon after conception;
- runs incorrectly or after the expiration date ;
- urine is too diluted due to excessive fluid ingestion ;
- the woman is taking certain medicines (such as diuretics or antihistamines ).
Conversely, taking contraceptives, antibiotics or alcohol or drugs does not distort the test result.
What to do to avoid false negatives?
1. Don’t rush!
A test must be done at the right time . We often read of tests done a few hours after the risky intercourse or within a week of it. In these cases the results will certainly be negative, even if a pregnancy has occurred.
If you have a regular cycle, the main rule is to wait at least the first day of delay before taking a pregnancy test . This will make it more likely that your beta hCG level has reached levels that can be diagnosed with a urine test.
If, on the other hand, you have an irregular cycle , it would be ideal to wait one day longer than your longest cycle . For example, if the duration of your cycle varies from 22 to 33 days, the advice is to wait for the 34th.
Of course, even for those who have a regular cycle it can still happen that ovulation occurs a few days late . In this case, the test may still give a false negative. If possible pregnancy symptoms appear or menstruation does not occur within a week, the suggestion is to repeat the test.
2. Take the test the right way
Always follow the instructions indicated on the package and wait the expected time before reading the result. Also, remember never to reuse the same test after use.
3. Pay attention to the expiration date
Avoid using expired pregnancy tests as they may give you unreliable results . Also, make sure the tests you buy are quality .
4. Don’t drink too much before the test
Too diluted urine can cause a false negative. For this, avoid drinking too much before going to sleep and take the pregnancy test as soon as you wake up, with your first urine in the morning .
What to do if the test is negative but menstruation does not come?
In addition to pregnancy, there are other reasons why your period may not come (amenorrhea), such as stress , excessive exercise , weight loss , ovarian problems or thyroid disease .
For this reason, if the test is negative and menstruation still does not occur, it is important to consult your doctor .
Kathryn Barlow is an OB/GYN doctor, which is the medical specialty that deals with the care of women's reproductive health, including pregnancy and childbirth.
Obstetricians provide care to women during pregnancy, labor, and delivery, while gynecologists focus on the health of the female reproductive system, including the ovaries, uterus, vagina, and breasts. OB/GYN doctors are trained to provide medical and surgical care for a wide range of conditions related to women's reproductive health.