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A universal freeze all strategy: why it is not warranted
1aDepartment of Obstetrics and Gynecology, Koc University School of Medicine, Istanbul, Turkey bDepartment of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, Connecticut, USA.
Current Opinion in Obstetrics & Gynecology
|March 24, 2017
Summary
Elective frozen embryo transfer (eFET) in assisted reproductive technology may not improve live birth rates for all patients. Current evidence is low quality, suggesting a universal eFET strategy is not yet justified.
Area of Science:
- Reproductive Endocrinology
- In Vitro Fertilization
Background:
- Preclinical data suggest multifollicular growth may negatively impact endometrial function in assisted reproductive technology (ART).
- Universal elective frozen embryo transfer (eFET) is increasingly promoted, irrespective of patient or cycle characteristics.
Purpose of the Study:
- To review the clinical evidence regarding the effectiveness and safety of eFET in ART cycles.
- To evaluate the justification for a universal eFET strategy.
Main Methods:
- Review of randomized controlled trials (RCTs) and other studies comparing fresh embryo transfer with eFET.
- Analysis of data stratified by ovarian response (normal, low, or excessive).
Main Results:
- RCTs comparing fresh versus eFET show contradictory results for live birth rates, primarily in hyper-responder populations.
- Studies including normal or low responders are often retrospective and prone to bias, also yielding conflicting outcomes.
- Recent research indicates potential risks associated with eFET, including hypertensive disorders, placenta accreta, and increased perinatal mortality.
Conclusions:
- The existing evidence supporting the advantages of eFET is of low quality.
- A universal eFET strategy is not currently supported by robust clinical data.
- Further high-quality RCTs are necessary, particularly in diverse patient populations with varying ovarian responses.
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