Pregnancy tests are most reliable from the first day of your missed period, although some tests can be used as early as 4 or 5 days before your period is due.
Check the packaging of your test to find out when it can be used.
If you have regular periods, you'll probably know when your next period is due.
If you're not sure, it's a good idea to wait at least 3 weeks after you think you may have conceived before doing a test.
Read more about doing a pregnancy test.
Pregnancy test results
A positive test (pregnant) result is almost certainly correct. A negative (not pregnant) result is less reliable.
If you still think you're pregnant after a negative result, wait a few days and try again.
If you keep getting negative results, but you're worried about your period being late, speak to your GP.
For more information, see How accurate are home pregnancy tests?
When did I conceive?
Pregnancy tests check for the presence of the pregnancy hormone, human chorionic gonadotrophin (HCG), in your urine. Your body begins to produce HCG after you conceive.
If you get a positive test result on the first day of your missed period, it's probably about 2 weeks since you conceived.
You can use the pregnancy due date calculator to work out when your baby is due.
More sensitive tests may be able to confirm that you're pregnant from as early as around 8 days after conception.
Some pregnancy tests can give an estimation of when you might have conceived based on the level of HCG in your urine.
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Page last reviewed: 24 September 2018
Next review due: 24 September 2021