Antibodies to HCG are precoated onto membrane as a capture reagent on the test zone. During the test, specimen is allowed to react with the colloidal gold particles, which have been labeled with antibodies to HCG. If HCG is present, a red colored line will develop on the membrane in proportion to the amount of HCG present in the specimen. To serve as a procedural control, red colored line in the control zone will always appear regardless of the presence of HCG. In normal pregnancy, HCG can be detected in urine after fertilization. Usually, concentration of HCG in urine is at least 25mIU/ml as early as seven to ten days after conception. The concentration increases steadily and reaches its maximum between the eighth and eleventh weeks of pregnancy. The appearance of HCG soon after conception and its subsequent rise in concentration during early gestational growth make it an excellent marker for the early detection of pregnancy.