A very shallow test paper test on the eighth day of fresh embryo transfer is generally normal and usually indicates a high likelihood of successful transfer. Due to the short time of implantation, the concentration of HCG in the blood is relatively low, so it shows weak positivity in urine test, resulting in a very shallow test paper. After blastocyst implantation, it usually takes 5-7 days to complete implantation, and after implantation, trophoblast cells start to secrete HCG, which can be detected in urine only when HCG reaches a certain concentration in the blood. In the above case, it is generally recommended to test again after 3 days, if the color becomes darker, it suggests that the embryo is well developed. If the test paper is very light on the eighth day of fresh embryo transfer, accompanied by abdominal pain and other discomforts, it is recommended to consult a doctor in time, under the guidance of the doctor, improve the relevant tests, clarify the cause of the disease, and take the appropriate measures to deal with it.