Embryos are often transferred on day 3 of culturing in many clinics. However, embryos can be cultured for longer to a blastocyst stage around day 5. Transfering a blastocyst allows the embryologist to gather extra information regarding the potential of the embryos, so that the strongest embryo can be selected for transfer in order to give you the best chance to conceive. At TFP we now culture all embryos to day 5 to give our patients the best chance of success.
Day 3 and day 5 embryos are two distinct cell types:
Cleavage stage embryo
Day 2 to 3 of development – Consists of 2-8 cells.
Blastocyst stage embryo
Day 5 of development – Consists of more than 100 cells.
Improved selection for embryo transfer
Increased chance of filtering out abnormal embryos
Better synchronisation of embryo stage with the female tract.