How We Decide When to Transfer Embryos
By Francis Polansky, M.D.
Eggs retrieved as a part of In Vitro Fertilization are combined with sperm six hours after egg retrieval. The following day, eggs that fertilized are classified as Day #1 embryos. Ideally, embryos should reach the “Blastocyst” stage by Day #5. Blastocyst (80 or more cells) is an embryonic developmental stage just before an embryo hatches out of its egg shell. Transfer of embryos inside the uterus can be done anytime from Day #1 to the blastocyst stage (Day #5).
The goal of accurate timing of embryo transfer is to maximize the probability of a successful outcome whether from “fresh” (unfrozen) or cryopreserved embryos and to minimize the likelihood of an undesirable multiple pregnancy.
At Bay IVF, we have developed and use a complex algorithm based on our 25+ years of clinical experience in advanced reproductive treatments. This algorithm, together with each patient’s unique reproductive circumstances, guides us in precise timing of embryo transfers. Most patients will have their embryo transfer on embryonic Day #2, #3, or #5.
In selecting the optimal embryo transfer day, we consider the following factors:
Age of the patient providing eggs
Length of infertility
Cause(s) of infertility
Any previous reproductive treatments and their outcome
Number of embryos available for transfer
Speed of development of available embryos
Degree of synchronization between the development of endometrial lining and the embryos
Blood progesterone level (related to synchronization with endometrial lining)
Some patients whose progesterone level is too high, or whose embryos develop too slowly to the blastocyst stage, will have all of their embryos vitrified (cryopreserved) and will have a Cryopreserved Embryo Transfer treatment in a subsequent cycle.
We will communicate to you which day you will have your embryo transfer as soon as the date becomes known to give you as long a notice as possible. Your embryo transfer appointment is a brief visit with no physical restrictions and no need for pain medications.
Please call or email us if you are interested in finding more about the art of embryo transfer timing.