Outcomes after frozen embryo transfer failure: changing the protocol does not improve live birth

Area of Science:

• Reproductive Endocrinology
• In Vitro Fertilization (IVF)

Background:

• Frozen embryo transfer (FET) is a key component of assisted reproductive technology.
• Women who do not achieve live birth after an initial FET often undergo subsequent cycles.
• Endometrial preparation protocols for FET can vary, including programmed and natural cycles.

Purpose of the Study:

• To investigate if altering the endometrial preparation protocol for frozen embryo transfer (FET) affects pregnancy outcomes in women with a prior failed FET.
• To compare pregnancy outcomes between repeating the same FET protocol and switching to a different protocol after an initial unsuccessful FET.

Main Methods:

• Retrospective cohort study analyzing 17,989 FET cycles from 2012 to 2022.
• Patients were categorized into four groups based on initial and subsequent FET protocols (programmed vs. natural).
• Primary outcome was live birth; secondary outcomes included clinical pregnancy and pregnancy loss.

Main Results:

• No significant difference in live birth rates was observed when switching from a programmed FET to a natural FET, or vice versa, after an initial failed FET.
• Repeating the initial FET protocol versus switching protocols showed comparable rates of live birth, clinical pregnancy, and pregnancy loss.
• A subgroup analysis indicated a potential benefit for live birth rates when switching to a 'true' natural FET protocol after a failed programmed FET.

Conclusions:

• Changing or repeating the FET protocol after an initial failed attempt does not significantly alter live birth, clinical pregnancy, or pregnancy loss rates.
• The choice of FET protocol (programmed vs. natural) may not be the primary determinant of success after an initial failure.
• Further research is warranted to elucidate the specific impact of 'true' natural FET protocols on pregnancy outcomes.