Embryos of poor quality are recommended for transfer, and sac keeping is not recommended. Bladder retention means that the embryo on the 3rd day continues to be cultured in vitro, and is cultured to form blastocysts on the 5th~6th day. Bladder retention has certain benefits, and it enables the cells to continue to divide, and generally, blastocysts with more than 100 cells will be formed on the 5th~6th day, and then the transfer is carried out at this time, which can increase the probability of success, and it can also reduce the occurrence of ectopic pregnancies. However, if the quality of embryos is not good, it is possible that the feeder sacs will stop developing during the process of blastocyst culture, which will result in a situation where there are no embryos to be transferred, so it is recommended to transfer the embryos in time if they are not of good quality so that there is still a certain chance of success. There are more factors to consider whether to transfer or to raise the sacs during IVF, it is recommended to choose the appropriate treatment under the guidance of the doctor to try to improve the patient’s transfer success rate, during IVF it is recommended to relax, keep optimistic mood and avoid too much anxiety.