How accurate are home pregnancy tests?

Home pregnancy tests are accurate as long as you follow the instructions correctly.

A positive test result is almost certainly correct. However, a negative test result is less reliable.

The result may not be reliable if you:

  • don't follow the instructions properly
  • take the test too early

Some medications can also affect the results.

Carrying out a test

When you become pregnant, your body produces a sudden increase of a hormone called human chorionic gonadotrophin (HCG, known as the "pregnancy hormone"). Home pregnancy tests detect this surge of HCG in your urine.

You can take most pregnancy tests from the first day of your missed period. Tests carried out earlier than this are not always accurate. For more information, see How soon can I do a pregnancy test?

Check the instructions to make sure you can do the test at any time of day. It's usually best to take the test first thing in the morning as your urine will have the highest concentration of hormones at this time.

Avoid drinking too much fluid beforehand, as this can dilute the level of HCG in your urine.

Positive test results

If the test result is positive, you're almost certainly pregnant. Contact your GP surgery as soon as possible. Because home pregnancy tests are so accurate, your GP may not repeat the test.

If you're not sure whether you want to continue with the pregnancy, you can find more information about your options here: Am I pregnant?

If you want to know when the baby is due, you can use our pregnancy due date calculator.

Negative test results

If the test result is negative, you may not be pregnant. However, negative results are less reliable. For example, if you do a pregnancy test too early, you could be pregnant, but there may not be enough HCG in your body to give a positive test result.

Pregnancy tests vary in their sensitivity (how soon they can detect HCG and what level of HCG needs to be present). You can find information on the packaging about how sensitive your test is.

If you still think you're pregnant after a negative result, wait a few days and try again. Speak to your GP if you get a negative result after a second test but your period hasn't started.

Medications

Some medicines can cause you to get a positive result even if you are not pregnant. These include:

  • promethazine – used to treat conditions such as allergies
  • medicines used to treat Parkinson's disease 
  • anti-anxiety medicines such as diazepam
  • antipsychotics medicines such as clozapine
  • diuretics (medicines that increase the amount of urine produced) – used to treat conditions such as heart failure
  • anticonvulsants (medicines that prevent seizures or fits) – used to treat conditions such as epilepsy  
  • medicines used for infertility 

If you're taking any medication, the patient information leaflet that comes with it will tell you if it affects test results. You can also ask a pharmacist.

Early miscarriage

If your first pregnancy test result is positive, but a later one is negative or your period starts, it's possible you've had an early miscarriage. Speak to your GP or midwife for advice.

Further information:

Page last reviewed: 13/11/2018
Next review due: 13/11/2021