Frozen versus Fresh Embryo Transfer in IVF: A Systematic Review of Live Birth Rates

Abstract

Introduction: In in-vitro fertilization (IVF), a "freeze-all" strategy with subsequent frozen embryo transfer (FET) has been proposed to improve outcomes compared to traditional fresh embryo transfer. This review compares the efficacy of these two approaches.

Methods: A systematic search for RCTs was conducted, comparing a freeze-all strategy (FET) to a fresh embryo transfer strategy in women undergoing IVF. The primary outcome was the live birth rate per initiated cycle.

Results: The meta-analysis of numerous RCTs showed that in high-responder patients (e.g., those with PCOS), the FET strategy was associated with a significantly higher live birth rate and a lower risk of ovarian hyperstimulation syndrome (OHSS). In normal responders, there was no significant difference in live birth rates between the two strategies.

Discussion: The benefit of a freeze-all approach appears to be confined to high-responder patients, where avoiding a fresh transfer in a hyperstimulated hormonal environment is advantageous. For most patients, a fresh transfer remains a valid option.

Conclusion: A freeze-all strategy with frozen embryo transfer improves live birth rates in high-responder IVF patients.