Elective frozen replacement cycles for all: ready for prime time?

Area of Science:

• Reproductive Endocrinology and Infertility
• Embryology and Cryopreservation

Background:

• Traditional in vitro fertilization (IVF) practice involves transferring embryos in fresh cycles, with cryopreservation reserved for surplus embryos.
• Advances in cryopreservation technology have improved success rates for frozen embryo transfer (FET) cycles, nearing those of fresh cycles.
• Observational data indicate potentially superior obstetric and perinatal outcomes in pregnancies conceived via FET.

Purpose of the Study:

• To evaluate the feasibility and safety of a 'freeze-all' strategy for all IVF embryos.
• To explore the biological rationale and existing evidence supporting a shift from fresh to frozen embryo transfers.
• To consider the implications of implementing a universal FET strategy in routine IVF clinical practice.

Main Methods:

• Review and appraisal of existing randomized controlled trials (RCTs) comparing fresh versus frozen embryo transfer outcomes.
• Exploration of biological mechanisms potentially influencing feto-maternal outcomes in different transfer strategies.
• Discussion of the clinical and practical considerations for adopting a 'freeze-all' approach.

Main Results:

• Current randomized trials suggest a potential benefit for frozen embryo transfer strategies.
• The success rates of FET cycles are increasingly comparable to fresh cycles.
• Observational studies consistently report better feto-maternal safety profiles with FET.

Conclusions:

• A 'freeze-all' strategy warrants consideration for enhancing feto-maternal safety in IVF.
• While current evidence leans towards favoring FET, larger-scale randomized trials are essential.
• Further research is required before a definitive recommendation for widespread clinical adoption can be made.