A blastocyst is an embryo at an advanced stage of physiologic development when there are two cells present : one group of cells that form the placenta, and another group of cells that form the fetus. Advances by our superb IVF laboratory staff have been able to provide proper nutrients to grow embryos to this advanced stage of development. The further the developed embryos, the better your ability to select the healthiest and most viable embryos, while transferring a smaller number of embryos. This will allow us to maintain or raise pregnancy rates while reducing the number of embryos returned by reducing the most significant complication - multiple pregnancy.

Why does the blastocyst stage have a higher implantation rate than two-to four- cell stage embryos?

Not all fetilized oocytes are normal, and therefore a percentage always exists that are not destined to establish pregnancy. The majority of such abnormalities are chromosomal. It has been determined that around 25% of the chromosomes are abnormal and that this problem worsens with maternal age. The culmination of this is that many abnormal embryos arrest or stop growing during development. So by culturing embryos to the blastocyst stage, one has already selected against all those embryos with little if any development potential. Therefore, a blastocyst has a higher implantation rate.