Fresh or frozen embryo transfer?
Embryo transfer is carried out on the 3rd or 5th day after egg collection and it is included in the definition of fresh embryo transfer. In frozen embryo transfer, the embryos obtained are frozen using fast freezing techniques called vitrification, and intrauterine tissue called endometrium is prepared and transferred in one or subsequent cycles.
It is stated that the environment created by the high level of estrogen hormone that occurs during ovulation stimulation in the transfer of fresh embryos decreases the probability of pregnancy in the intrauterine tissue, and then the possibilities such as preterm birth, low, overweight baby increase. However, it should be said that there is not enough evidence in publications on this issue.
Frozen embryo transfer is already preferred in cases such as hyperstimulation syndrome development during treatment, polyp development in the endometrium, multiple in vitro fertilization attempts to create an embryo pool. However, postponing embryo transfer is not a routine practice to increase pregnancy rates. Because the studies on the subject are not enough to evaluate this subject within the framework of evidence-based medicine and more studies are needed.
However, frozen embryo transfers with these or other indications are very successful with laboratory systems that apply vitrification (rapid freezing) techniques well. By discussing this issue with the couple, it will be correct to evaluate and decide the special conditions of the couple.