After the egg is fertilised, it travels to the uterus (womb) and implants itself in the uterine wall. At this stage tiny amounts of the pregnancy hormone, hCG, start to appear in your urine. It is this hormone that all home pregnancy tests detect and some tests are so sensitive that they can be used up to 6 days before your missed period (which is 5 days before your expected period).
So, for example, if you expect your period on 15th of the month, you can test as early as the 10th. Use our helpful ‘when to test’ calculator to find out when you can test with Clearblue Early Detection Pregnancy Test – no test can tell you sooner. No matter when you test, you can be confident in the accuracy of a ‘Pregnant’ result with any Clearblue Pregnancy Test.
But if you are testing early, you should be aware that even if your result is not pregnant, you may still be pregnant. This is because levels of hCG vary from woman to woman and there may not yet be enough hormone for the test to give a positive result. HCG levels rise rapidly in early pregnancy, as shown in the graph below, meaning that if you test again on the day of your expected period, your result (whether positive or negative) will be over 99% accurate.