Embryo Transfer - Timing

Timing

In stimulated cycles in human IVF, embryos are typically transferred 3 days after fertilization and may then be at the eight-cell stage, or they are transferred 2 to 3 days later when they have reached the blastocyst stage. Embryos who reach the day 3 cell stage can be tested for chromosal or specific genetic defects prior to possible transfer by preimplantation genetic diagnosis (PGD).

Monozygotic twinning is not increased after blastocyst transfer compared with cleavage-stage embryo transfer.