Blastocyst Transfer with IVF
A blastocyst is an embryo on Days 5-7 of cell division in which two types of cells are present — a group that form the placenta and a group that form the fetus. With recent advances in assisted reproductive technology, IVF laboratory staff now have the means to grow embryos in the proper nutrients to this advanced stage of development before transferring them into a woman's uterus.
The blastocyst transfer is an in vitro fertilization (IVF) technique that was developed to increase pregnancy rates and decrease the risk of multiple pregnancy. If the embryos are grown in the lab to the blastocyst stage, they are highly developed and ready to hatch out of the zona pellucida and attach to the uterine wall (implantation).
In conventional IVF, embryos are usually only grown in the IVF lab for two or three days before they are transferred into a woman's uterus, where they must continue growing and developing for four or five more days before they become blastocysts and are ready to implant. At this early stage of development, it is more difficult for an embryologist to determine which embryos will have the greatest success at growing into blastocysts and implanting, which is why more embryos (two to three) are usually placed in the uterus, which increases the risk of multiples.
By keeping embryos in the IVF laboratory for a few more days, the embryologist can better determine which embryos have successfully developed into blastocysts and have a greater likelihood of implanting. Many abnormal embryos will stop growing during development before they reach the blastocyst stage, so by growing embryos to the blastocyst stage, that embryo has the higher potential of developing into a successful pregnancy and a healthy baby.