What do the two bars mean?

Pregnancy test is a convenient product for women to test whether they are pregnant. As a preliminary screening test, it occasionally shows false positive or false negative. The principle of the test is to apply the principle of immunochromatographic double antibody sandwich method to make hcg test paper. It can determine hcg in urine samples within three minutes. Collect urine in disposable urine cups and clean containers, remove the test paper for testing, dip the end of the test paper with arrow mark into the container containing urine sample, and remove it after about three seconds. If the pregnancy test has two bars, it indicates pregnancy. If the pregnancy test shows a purple color at the upper end and no color band at the lower end, it indicates that it is not pregnant. If no color band is shown, it indicates that the test strip has failed.