Embryo is usually in the blastocyst stage on day five after fertilization. The embryo reaches the uterus through fallopian tubes in this stage of pregnancy in a natural pregnancy. Extended cultivation and transfer on day five or six after fertilization, not as soon as day three, therefore imitates the course of natural pregnancy. Only a third of embryos reaches the blastocyst stage and that is why the extended cultivation can be considered a method of selection of high-quality embryos. This procedure increases the chance of successful treatment by 10 – 15%.
What are other advantages of extended cultivation?
- cells collected from the blastocyst surface on day five after fertilization are suitable for genetic testing
- blastocysts can be frozen with vitrification and stored with a good prospect of development after thawing for future cycles