In normal transfer, we transfer the embryos after 2 to 3 days of cultivation in the laboratory. Prolonged cultivation lasts for 5 to 6 days and we have much better results with it.
Up to 30% of the embryos which develop properly in the first 3 days of cultivation, do not take hold after transfer to the uterus. By cultivating the embryos longer and not transferring them to the uterus until the 5th or 6th day, we create more favorable conditions for their attachment to the uterine lining.
After a natural pregnancy, the embryo travels to the uterus as soon as it enters the so-called blastocyte phase, also after 5 days of development. With prolonged cultivation, we let the embryo reach the blastocyst stage, thus simulating the natural development of pregnancy.
Another advantage is that from embryos that have undergone prolonged cultivation, we can remove cells needed to perform a pre-implant genetic examination (PGD / PGS).