A blastocyst is an embryo that has advanced to day 5 or 6 development and whose cell number has substantially increased and whose cells have differentiated.
What advantages does it offer?
In a natural pregnancy, fertilization occurs in the Fallopian tubes and the embryo develops and moves towards the uterus. On day 5 after embryo fertilization, when the embryo has become a blastocyst, it gets to the uterine cavity. On day 6, implantation occurs in the endometrium. So as for the cycle to be as close to a natural cycle as possible, it is recommended that the embryo transfer be performed at this time. Furthermore, an embryo in the lab that gets to day 5 of development is a good embryo with excellent quality and implantation potential. Thus, a blastocyst transfer increases the probability of implantation.
The sequential culture to blastocyst allows the selection of the embryo of best quality and category.