In recent years, technological advances in the embryology laboratory enabled the extension of the stay of embryos in the laboratory environment to the 5th - 6th day.
The potential advantages of the embryo transfer on day 5 are plenty.
• The blastocysts lead more often to pregnancy because the more the embryos remain in the laboratory, the more clear is which of them are the best.
• The inside of the uterus is more contemporary with the embryo's stage of development.
• The use of the embryoskopisis and the detailed observation of the evolution of the embryos to the blastocyst stage, can make the selection of the embryos with the highest implantation chances even better.
However, there is always the chance that none of the embryos would be able to reach the blastocyst stage, having as a concequence the termination of the treatment cycle without any embryo transfer. Only a woman who has several good embryos on day 3 it makes sense to wait until the fifth and only if the laboratory is experienced in prolonged embryo culture.