Rapid pregnancy tests (test strips) determine the level of hCG in the urine. These strips contain specific antibodies to this hormone. If the level of human chorionic gonadotropin in the urine exceeds the sensitivity of the test, the strip is colored. This means that there is a pregnancy.
It is possible to determine the level of hCG in urine with high probability starting from the fifth day of delay.
The rapid test demonstrates the fact of an increase in human chorionic gonadotropin, but does not measure its level. Only a laboratory blood test can determine its concentration.
It should be taken into account that pharmacy test strips can give a false positive result. For example, if a woman is taking medications containing hormones, the test may respond to this with the appearance of a second strip.