Only 5 embryos are needed to raise the sacs, because raising the sacs to a certain level and then transferring them can improve the success rate of doing IVF. Bladder raising is the process of continuing to grow day 3 embryos in vitro into day 5~6 blastocysts before transfer, which usually requires 3~5 embryos. The structural complexity of embryos after bladder raising treatment has increased, and the embryos have become more stable as a result, and the success rate of embryo transfer will be relatively higher. Therefore, in order to increase the success rate of pregnancy, it is necessary to raise embryos. Pregnant women are advised to relax during the transfer process and before and after the transfer, avoid excessive anxiety, and seek timely medical attention and complete the relevant examinations in case of abnormalities.