For an early test (which can be done about 4 days before the usual onset of your period), it is recommended to use the first morning urine. Because in the first urine after getting up in the morning, the hormone hCG, which is generally not that high in the beginning of pregnancy, is most concentrated. However, such an early test is not particularly accurate because it has a high error rate. It is therefore recommended to do a pregnancy test from the day your period is due.

With a urine test from the day on which your period should start, it does not matter which particular urine is used for the test – because if you are pregnant, the hormone hCG will be consistently high then.