Endometrial receptivity in women of advanced age: an underrated factor in infertility

Abstract

BACKGROUND Modern lifestyle has led to an increase in the age at conception. Advanced age is one of the critical risk factors for female-related infertility. It is well known that maternal age positively correlates with the deterioration of oocyte quality and chromosomal abnormalities in oocytes and embryos. The effect of age on endometrial function may be an equally important factor influencing implantation rate, pregnancy rate, and overall female fertility. However, there are only a few published studies on this topic, suggesting that this area has been under-explored. Improving our knowledge of endometrial aging from the biological (cellular, molecular, histological) and clinical perspectives would broaden our understanding of the risks of age-related female infertility. OBJECTIVE AND RATIONALE The objective of this narrative review is to critically evaluate the existing literature on endometrial aging with a focus on synthesizing the evidence for the impact of endometrial aging on conception and pregnancy success. This would provide insights into existing gaps in the clinical application of research findings and promote the development of treatment options in this field. SEARCH METHODS The review was prepared using PubMed (Medline) until February 2023 with the keywords such as ‘endometrial aging’, ‘receptivity’, ‘decidualization’, ‘hormone’, ‘senescence’, ‘cellular’, ‘molecular’, ‘methylation’, ‘biological age’, ‘epigenetic’, ‘oocyte recipient’, ‘oocyte donation’, ‘embryo transfer’, and ‘pregnancy rate’. Articles in a language other than English were excluded. OUTCOMES In the aging endometrium, alterations occur at the molecular, cellular, and histological levels suggesting that aging has a negative effect on endometrial biology and may impair endometrial receptivity. Additionally, advanced age influences cellular senescence, which plays an important role during the initial phase of implantation and is a major obstacle in the development of suitable senolytic agents for endometrial aging. Aging is also accountable for chronic conditions associated with inflammaging, which eventually can lead to increased pro-inflammation and tissue fibrosis. Furthermore, advanced age influences epigenetic regulation in the endometrium, thus altering the relation between its epigenetic and chronological age. The studies in oocyte donation cycles to determine the effect of age on endometrial receptivity with respect to the rates of implantation, clinical pregnancy, miscarriage, and live birth have revealed contradictory inferences indicating the need for future research on the mechanisms and corresponding causal effects of women’s age on endometrial receptivity. WIDER IMPLICATIONS Increasing age can be accountable for female infertility and IVF failures. Based on the complied observations and synthesized conclusions in this review, advanced age has been shown to have a negative impact on endometrial functioning. This information can provide recommendations for future research focusing on molecular mechanisms of age-related cellular senescence, cellular composition, and transcriptomic changes in relation to endometrial aging. Additionally, further prospective research is needed to explore newly emerging therapeutic options, such as the senolytic agents that can target endometrial aging without affecting decidualization. Moreover, clinical trial protocols, focusing on oocyte donation cycles, would be beneficial in understanding the direct clinical implications of endometrial aging on pregnancy outcomes.

Evaluation of the Impact of Letrozole in Combination with the GnRH Antagonist Ovarian Stimulation Protocol in Patients Expected to Have a Poor Ovarian Response (POSEIDON Groups 3 and 4)

“…However, similar to our findings, they also observed a non-significant decline in implantation rate when letrozole was used in POSEIDON group 4 patients. This disparity in implantation rates appears to be attributed to the influence of aging on endometrial receptivity rather than the administration of letrozole [ 27 ].…”

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

“…The multiple causes of infertility have led to a focus on maintaining cyclic endometrial repair. In the next section, we will summarize the phases menstrual cycle 52 …”

Comparing Clomiphene-Primed Ovarian Stimulation and Mid-Luteal GnRH Agonist Protocols: A Cumulative Live Birth Rate and Cost-Effectiveness Analysis in a Single- Center Retrospective Study with Propensity Score Matching

“…In the outcomes of the embryonic laboratory, the CPOS group had signi cantly fewer retrieved oocytes and a signi cantly higher rate of oocyte maturation than the GnRHa group [6(4, 10) vs. 11 (7,11), p<0.001; 88.89% (75%, 100%) vs. 85.71% (72.73%, 100%), p = 0.001, respectively]. However, there were no signi cant differences in normal fertilization rate, cleavage rate, top-quality embryo rate and blastocyst formation rate between the two groups.…”