The level of hCG varies throughout the day, reaching a minimum concentration in the afternoon. After a few days of delay, this will not matter, but in the early days, the concentration of the hormone in the afternoon may not be sufficient to diagnose pregnancy.
Experts advise to conduct a home express test in the morning, when the hCG level is maximum. To reduce the chance of error, you should not drink a lot of liquid before the diagnosis. The test will show pregnancy during the day, but in the early stages, the strip may be too weak, slightly noticeable. In order to be sure, it is better to follow the rules.