Embryo transfer to the patient's uterus can be performed on day 3 or day 5. Each of these options has its advantages and disadvantages.
Among the disadvantages of transferring on day 3 is that it is not known whether the embryo will stop developing in the uterus after the transfer. Thus, less information is obtained about embryo development than if transferred on day 5.
In addition, when transferring on day 3, it may be common to transfer two embryos, which increases the likelihood of obtaining a multiple pregnancy that poses risks to the mother and the babies.