If a patient determines pregnancy by checking the blood chorionic gonadotropin, however, the pregnancy is not detected by using David’s test paper. In this case, the following possibilities are considered: First, the pregnancy is relatively short, so the urine pregnancy test cannot be detected. Under normal circumstances, it takes about 1 week for the fertilized egg to implant, and pregnancy can be detected by blood chorionic gonadotropin 1-2 days after implantation, but the urine pregnancy test does not detect it, and it is necessary to wait for about 3 days before pregnancy can be detected by the urine pregnancy test. Secondly, consider that the quality of David’s test paper used by the patient is not up to par or the test method is not appropriate, therefore, a false negative result occurs, you can change another test paper and continue testing again with morning urine. Third, it should be considered that the patient may have made a mistake in checking the blood chorionic gonadotropin and is not actually pregnant.