Glossary · Definition · v2026.3
What Is Blastocyst Transfer?
Blastocyst transfer is the placement of a five-day-old embryo into the uterus during IVF treatment.
Why Day Five
Embryos that reach the blastocyst stage by day five have demonstrated stronger developmental potential than earlier-stage embryos. The extended culture period allows embryologists to select the most viable embryos for transfer. Blastocyst transfer has become the standard of care in most IVF programs.
Blastocyst Transfer vs Day Three Transfer
Day three embryos contain six to eight cells. Blastocysts contain over one hundred cells and have differentiated into two structures: the inner cell mass and trophectoderm. While fewer embryos survive to day five, those that do have higher implantation rates per transfer. The trade-off is that some cycles may have no blastocysts available if embryos arrest before day five.
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This content defines terminology for educational orientation. It does not constitute medical advice.
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