Low Dose hCG Support in Modified Natural Frozen Embryo Transfer Cycles

Area of Science:

• Reproductive Endocrinology
• Assisted Reproductive Technology
• Clinical Obstetrics and Gynecology

Background:

• Modified natural frozen embryo transfer (mNC-FET) cycles utilize letrozole for endometrial preparation.
• Luteal phase support is crucial for successful implantation and pregnancy in FET cycles.
• The role of additional human chorionic gonadotropin (hCG) in supporting luteal phase in mNC-FET requires further investigation.

Purpose of the Study:

• To evaluate the effect of a single low-dose recombinant hCG injection administered post-embryo transfer (ET) in letrozole-induced mNC-FET cycles.
• To determine if this intervention improves ongoing pregnancy rates (OPRs) compared to standard luteal support.

Main Methods:

• An observational, quasi-randomized study included 154 women undergoing letrozole-induced mNC-FET.
• Ovulation was triggered with recombinant hCG; luteal support included dydrogesterone.
• The intervention group received an additional 3250 IU recombinant hCG on day 3 post-ET; controls did not.

Main Results:

• The hCG group demonstrated a significantly higher ongoing pregnancy rate (46.7%) compared to the control group (33.6%) (p=0.03).
• Demographic data, serum progesterone levels, and embryo transfer numbers were comparable between groups.
• No significant differences in baseline characteristics were observed, supporting the intervention's impact.

Conclusions:

• A single low-dose recombinant hCG injection after embryo transfer may enhance ongoing pregnancy rates in letrozole-induced mNC-FET cycles.
• This intervention could be a valuable addition to luteal phase support in specific FET protocols.
• Further research is warranted to confirm these findings and elucidate the precise mechanism of action.