For the first 2 decades of IVF, we always transferred embryos on the 2nd or 3rd day after egg retrieval. We were unable to routinely grow the embryos beyond this time. At this stage, the embryos were usually 4-8 cells and because at this stage it was difficult to choose the best embryos, we would often put 3-4 embryos in our patients. Success rates were not bad, however patients would not infrequently have triplets or more; this would lead to many medical, financial and psychological burdens on families. No, having triplets is not a good idea!
As a goal to increase pregnancy rates but eliminate triplets and decrease twins, we decreased the number of embryos to 1-2 embryos per transfer. Since this time we have tried to improve our ability to choose the best 1-2 embryos for transfer.
Recent advances in lab science technology have allowed us to be able to routinely grow the embryos for 2 additional days. At this time the embryos have reached the blastocyst stage and have already started to differentiate into future placental tissue and fetal tissue. Also, at this stage we are able to choose the best embryos for transfer more accurately. These advances in our lab, which have included using special media and limiting the time the embryos are out of the incubator has increased our ability to grow the embryos to blastocysts. Our ability to grow more blastocysts and our ability to choose the best 1 or 2 embryos has lead to much higher pregnancy rates.
In addition, our ability to freeze embryos via a new method at the blastocyst stage (vitrification) has lead to 90% survival of the embryos after warming them. This has also lead to a much higher pregnancy rate during a frozen embyo transfer cycle. For more info and details of how we choose the best embryos and our new freezing process, contact us today!