The endometrium in stimulated cycles for IVF

Area of Science:

• Reproductive Endocrinology
• Embryology
• In Vitro Fertilization (IVF)

Background:

• Ovarian stimulation for IVF significantly impacts luteal phase function.
• The endometrium in IVF cycles experiences an altered endocrinological environment.
• Factors influencing endometrial receptivity during IVF remain poorly understood.

Purpose of the Study:

• To investigate the effects of ovarian stimulation on endometrial development and receptivity in IVF cycles.
• To compare endometrial changes in IVF cycles with natural cycles.
• To identify key molecular markers and their clinical relevance for embryo implantation.

Main Methods:

• Comparative analysis of endometrial development in IVF versus natural cycles.
• Assessment of endometrial steroid receptor regulation.
• Evaluation of endometrial receptivity markers, including pinopodes, integrins, and leukemia inhibitory factor.

Main Results:

• IVF cycles exhibit premature secretory changes and asynchronous glandular-stromal differentiation.
• Ovarian stimulation leads to modified endometrial steroid receptor regulation and antiproliferative effects.
• Premature expression of receptivity markers like pinopodes and integrins is observed, but clinical relevance requires validation.

Conclusions:

• Ovarian stimulation profoundly modifies luteal endometrial development, potentially impacting receptivity.
• Severe advancement in endometrial maturation (over 3 days) in IVF cycles is linked to a lack of clinical pregnancies.
• Further research into implantation molecules is necessary to understand the link between altered endometrial development and IVF success.