How can we improve the implantation rates of human embryos in human IVF?
We cannot. All we can do is try to select the better ones so that the transfer will lead to a higher pregnancy rate. Some centers are experimenting with embryo biopsy and Aneuploidy screening to select the genetically soundest embryos. Other centers choose to culture the embryos to a later stage (the blastocyst stage) to select the best ones, and indeed both strategies seem to lead to higher implantation rates. These strategies, however, work only if a sufficient number of embryos are available. The major problem are still couples in whom only a low number of embryos can be obtained, since no selection can be performed there and the pregnancy rates will still remain low.
