Recent advances in blastocyst culture and transfer have resulted in improved IVF pregnancy rates and reduced multiple pregnancy rates.
What is a Blastocyst?
When an embryo reaches the 5 to 7 day development stage then a blastocyst is formed. At this point in development, the embryo has between 60 and 100 cells distributed in two areas. An outer embryo lining (which will later form the placenta), and an inner mass (which will later become the fetus). The embryo develops into the blastocyst stage during a natural cycle, as it is leaving the fallopian tubes and entering the uterus. An embryo needs to have entered into the blastocyst stage. Once it arrives in the uterus to ensure proper implantation.
Embryos are transferred to the uterus on day three (called Day 3 transfer) after fertilization and it is not uncommon to transfer 3 or 4 embryos. However, it is now possible to grow embryos in the laboratory to the blastocyst stage of development, which occurs on day 5 after fertilization. The strongest and healthiest embryos make it to blastocyst stage as they have survived the key growth and division processes. Plus they have a better chance of implanting once transferred. The selection of potentially more viable embryos allows the embryologist to transfer fewer embryos. Maybe 1 or 2, thus lowering the risk of high order multiples while maintaining high pregnancy rates.
Before you and your partner decide on a blastocyst culture and transfer, it is important to consider whether or not you are suited for the procedure. Your fertility specialist will perform a number of tests to determine whether you are suitable. You will also be advised of the risks involved so that you can make an informed decision. Blastocyst transfer (blastocyst culture) does have its disadvantages and may not be appropriate for all couples.