Pros of a Day 5 Blastocyst Transfer
By leaving the embryos in the lab until Day 5, the embryologist is better able to choose the better quality ones, which will provide a higher implantation rate while transferring fewer embryos. This offers the best chance of a pregnancy while reducing the chances of a high-order multiple pregnancy (triplets or more, which are high-risk pregnancies).
In an attempt to reduce the number of multiple or high-order pregnancies from IVF, more clinics are turning exclusively to blastocyst (day 5) transfer. The lab has to have an exceptionally good culture system that it trusts to grow embryos to the blastocyst stage as well as they would grow inside the body. If this is the case, it allows the embryo selection to be made at the end of the “race” when the more promising embryos become evident, which in turn increases the pregnancy rates for those who have an embryo transfer.
Cons of a Day 5 Blastocyst Transfer
The downside to waiting until Day 5 to do blastocyst transfer is that it is possible that all embryos stop growing before day five, leaving no embryos for transfer. This a devastating situation to face when a couple has made it so far through the IVF cycle.
This does not alter the outcome of the cycle. It is simply that the outcome is known prior to the embryo transfer. The positive aspect of this scenario is that the woman doesn’t have to wait two weeks until the pregnancy test, and potentially endure painful injections, only to find out that the embryos did not grow.