Letrozole Co-Administration in Progestin-Primed Ovarian Stimulation (PPOS) Protocols for Patients Undergoing In Vitro...

Area of Science:

• Reproductive Endocrinology
• In Vitro Fertilization (IVF)

Background:

• The standard Gonadotropin-Releasing Hormone agonist long protocol (PPOS) is widely used in IVF.
• Investigating modifications to PPOS, such as co-administration with letrozole (PPOS + LE), is crucial for optimizing ovarian stimulation outcomes.

Purpose of the Study:

• To systematically analyze and synthesize existing literature comparing the PPOS + LE protocol with the standard PPOS in patients undergoing IVF.
• To evaluate the impact of letrozole co-administration on ovarian stimulation and pregnancy outcomes.

Main Methods:

• Systematic literature search across major databases (MEDLINE, Scopus, EMBASE, Science Citation Index).
• Inclusion of five retrospective studies for analysis.
• Quality assessment using the Newcastle-Ottawa Scale.
• Primary outcomes: oocyte retrieval and maturation; Secondary outcomes: hormonal levels and pregnancy rates.

Main Results:

• PPOS + LE showed potential for increased oocyte retrieval and maturation in normal and poor responders (POSEIDON group 4).
• No significant benefit was observed in patients with Polycystic Ovary Syndrome (PCOS) or POSEIDON group 3.
• Variable efficacy suggests patient characteristics influence treatment response.

Conclusions:

• Letrozole incorporation in PPOS may counteract pituitary suppression, potentially increasing LH levels and oocyte yield in specific patient groups.
• The benefits of PPOS + LE are not universal and appear dependent on patient phenotypes (e.g., PCOS).
• Further prospective studies are required to validate these findings due to the retrospective nature of the current data.