Why does the hCG level of the test matter?
Not all home pregnancy tests are the same. The tests that detect the lowest concentration of hCG (in milli-International Units per milliliter of urine) are more sensitive to hCG and will give you the earliest reliable results. For example, tests that can detect 20 mIU/ml are more sensitive than those that can detect 50 to 100 mIU/ml.