How Many Embryos Should We Transfer?
By Francis Polansky, M.D.
Most human embryos, whether created through intercourse, artificial insemination, or In Vitro Fertilization, are not of a sufficient quality for implantation. Transferring (putting inside the uterus) more than one embryo in IVF treatment increases the likelihood that at least one embryo will implant.
In the US, there is no law that would limit the number of embryos to transfer, but at Bay IVF, we follow the recommendation of the American Society for Reproductive Medicine that most patients should transfer only one or two embryos.
There is no “crowding” effect inside the uterus. The more embryos you decide to transfer the higher the probability of pregnancy. But if you transfer two or more embryos, your treatment may result in a multiple pregnancy.
It is well known that a singleton pregnancy carries the lowest risk to the mother and newborn. Therefore, the delivery of a full-term, healthy singleton is considered the best outcome after the use of assisted reproductive technology treatments (i.e., IVF).
The number of embryos to be transferred is usually finalized during the embryo transfer visit to the clinic. At that time, the number of embryos available for transfer and their quality is known, and it is then possible to estimate the probability of a successful outcome.
The availability of successful embryo vitrification has resulted in many patients choosing to only transfer one or perhaps two embryos.
During your embryo transfer visit, you may be asked whether you are willing to get pregnant with a set of twins or triplets if it were to increase your probability of a life birth.
The answer to this question will determine whether only one, two, or perhaps three or more embryos should be transferred. We will always provide guidance, but you will have the final say in how many embryos to transfer.