Pregnancy Test: False Positives and False Negatives

By Medically reviewed by Dr. Duyen Le.

According to studies, many home pregnancy tests do not give accurate results in women who have recently missed a period. This is because they are not sensitive enough to diagnose pregnancy as people thought. For the most reliable result, you may want to wait until one week after you miss a period to take the test. But, there are two types of result that you may get. They include false positives and false negatives.

What are false positives?

A false positive is when a home pregnancy test showing that you get pregnant, but you are actually not. It could be the result of many reasons, such as menopause, an ectopic pregnancy or ovarian problems. Also, a false positive might occur because you had a pregnancy loss after a fertilized egg attached to your uterine lining. Or, when you take a pregnancy test soon after using a fertility drug which contains HCG – the human chorionic gonadotropin hormone that is often produced by the placenta after implantation.

What are false negatives?

This case is opposite to false positives. It means the result of a home pregnancy test shows you are not pregnant, while you are. You might have a false negative result if you:

Take the test too early. It is not the right time to take the test immediately after you have a missed period because it is hard for the test to detect HCG. Usually, after you missed your period one week, the level of HCG in your urine is likely to be detectable.
Check the test result too soon. It needs time to make the test work. So, checking the result sooner will not be helpful. Consider setting a timer according to the package instructions.
Use diluted urine. Morning is the best time for an accurate result because it’s when your urine is most concentrated.

What should you do next?

If you have a positive result or you have taken a few tests and the result make you confused, you may want to make an appointment with a doctor. With a blood test or ultrasound, you will know exactly your condition and plan for your pregnancy sooner.

But, if your home pregnancy test is negative and your period still does not come, you should take another test in a next few days or a week. The worse result is that you continue to get a negative result while your period does not come. You should check with your doctor as soon as possible. This could come from many reasons, such as thyroid disorders, low body weight, ovarian problems or stress. If you are not pregnant, your doctor may help you to get your period back on track.


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Hello Health Group does not provide medical advice, diagnosis or treatment.

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