I'm late on my period, and I took a pregnancy test and it reads negative…what can be wrong?

A urine pregnancy test detects only the presence of hCG. The amount of hCG in your urine can change over the course of the day depending on how much you drink and how diluted or concentrated the urine is. If your urine is too diluted, the amount of hCG may be inadequate for a positive result. Yes, a false negative pregnancy test can happen when testing is done too early or there is not enough hCG in the urine sample. It is important to follow the test instructions carefully. Your hCG level may be below the test’s hCG threshold. Or implantation may have occurred later, which will delay a positive result.