When a woman undergoes IVF, a little bleeding on the ninth day of transplantation may be caused by the implantation of the fertilized egg, or it may be the occurrence of preeclampsia, etc., which needs to be analyzed specifically. 1. Fertilized egg implantation: in IVF, embryo transfer, embryo transfer, if successful, may occur after the implantation of fertilized egg implantation, at this time will produce a certain degree of stimulation of the uterine lining, a small amount of intra-vaginal bleeding, but is not accompanied by other obvious discomforts. 2. Pre-eclampsia: If the fertilized egg has been implanted, at this time the development of the embryo is still unstable, may be under some external stimulation, there may be pre-eclampsia, at this time in addition to bleeding, there may also be back pain and abdominal pain and other obvious discomfort. If a small amount of bleeding occurs on the ninth day after embryo transfer, you need to go to the hospital in time to improve the relevant examination, under the guidance of the doctor to clarify the cause of the occurrence, and take targeted treatment.