5-Day Blastocyst Transfer

We let the embryos develop for five days then transfer the strongest ones.

DR. SMITH: A natural cycle, the embryo is fertilized high in the fallopian tubes. And it spends that first four days or so dividing and moving down the fallopian tube. And it gets into the uterus about late the fourth day early the fifth day. By that point it has reached the Blastocyst stage. A Blastocyst is a hollow ball of cells, approximately 60 to 100 cells. The cells on the outside of the Blastocyst are going to be responsible for attaching to the lining of the uterus and moving in and getting close to a blood supply and getting food for the developing embryo. But contained within that hollow ball of cells, stuck over on the side, rather unimaginatively named the inner cell mass, are the stem cells. These are the embryonic stem cells. And those are the cells from which the baby is going to come from. So when we wait until the Blastocyst stage, prior to transferring the embryos, we are confident that the embryo is capable of attaching and implanting. And if we take a look at the stem cells, we can assess the number of stem cells. And we can make sure there is an adequate number of stem cells in order to go the distance for a term pregnancy. There is another big advantage to waiting until the fifth or sixth day until the embryos reach the Blastocyst stage prior to transfer is that simply we attain a higher pregnancy rate and term delivery rate from transferring Blastocyst stage embryos. The implantation rate for Blastocyst stage embryos is about twice that of day three embryos. By simply waiting we can achieve the same level of pregnancy rates and term deliveries by transferring fewer embryos. This is a good thing because it also - - reduces the chances of triplets and quadruplets. We routinely transfer two embryos here. So twins can happen. Interestingly a lot of patients would like to have twins. And sort of one stop shopping and get it all done at once, instant family. This is not our goal because obstetrically twin pregnancies can be difficult. And so our philosophy is as many kids as you like, one at a time. But we do transfer two embryos. Walking that fine line between twin pregnancy rates and giving the patient a good chance of pregnancy.