After fertilization, embryos undergo a synchronized stage of development. Embryos are cultured until day 5 when normally a blastocyst is formed. At the blastocyst stage, two distinct cell types have been formed. One of these types will eventually comprise the fetus and the other the placenta.
With sufficient good quality embryos available, Blastocyst transfer allows a more selective criteria on choosing embryos to transfer. It allows the transferring of fewer high quality embryos, which reduces the risk of multiple pregnancies.
With extended culture of embryos there is an increased risk of embryo arrest and demise and therefore the balstocyst transfer should be discussed with your physcian. There is a list of criteria that determines if you are a good candidate for extending your embryo to blastocyst stage.
