Blastocyst Transfer
The embryo (fertilized egg) grows first by dividing into
2 cells then 4. After 3 days it usually has 8 cells. Thereafter
the number of cells increases rapidly, so that by the fifth
day most healthy embryos will have reached the blastocyst
stage, that is having more than 60 cells.
Many IVF practices perform embryo (or blastocyst) transfers
on day five, since this is the time during a natural pregnancy,
when the embryo would implant in the uterus. It is also
easier to select the best quality blastocysts. Usually only
two are transferred, reducing the risk of triplets or other
multiple pregnancies.
