Ideal frozen embryo transfer regime

Area of Science:

• Reproductive endocrinology and infertility research.
• Assisted reproductive technologies (ART) and embryo transfer protocols.

Background:

• Frozen embryo transfer (FET) is a key component of in vitro fertilization (IVF).
• Endometrial preparation is critical for successful FET outcomes.
• Various methods exist, each with distinct advantages and disadvantages.

Purpose of the Study:

• To compare evidence on different endometrial preparation methods for FET.
• To evaluate methods based on embryo implantation, obstetric outcomes, patient convenience, and IVF-unit efficiency.

Main Methods:

• Systematic review and analysis of published research on FET endometrial preparation.
• Comparison of artificial FET cycles, natural FET cycles, modified natural cycle FET (mNC-FET), and letrozole use.

Main Results:

• Artificial FET cycles offer scheduling and implantation advantages but may compromise obstetric outcomes.
• Natural FET requires accurate ovulation identification for implantation.
• mNC-FET, using hCG induction, enhances patient convenience by reducing monitoring visits.
• Letrozole is a cost-effective, well-tolerated option for anovulatory patients, preserving endometrial thickness.
• A novel approach combines natural and artificial cycle benefits for improved FET procedures.

Conclusions:

• No single FET preparation method is universally superior; the choice depends on individual patient factors and desired outcomes.
• Balancing scheduling convenience with optimal obstetric outcomes remains a key consideration in FET protocols.
• Emerging strategies aim to optimize both efficiency and success rates in frozen embryo transfer.