1. Progesterone in frozen embryo transfer cycles: assays, circulating concentrations, metabolites, and molecular action
- Author
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Rachel Mandelbaum, M.D. and Frank Z. Stanczyk, Ph.D.
- Subjects
Progesterone ,frozen embryo transfer ,assisted reproductive technology ,assay methodology ,metabolites ,Diseases of the genitourinary system. Urology ,RC870-923 ,Gynecology and obstetrics ,RG1-991 - Abstract
Programmed or medicated frozen embryo transfer cycles rely on exogenous progesterone (P) administration to prepare the endometrium for implantation and maintain pregnancy. Presently, the optimal route and dose of P replacement for frozen embryo transfer are not known. In addition, there is a paucity of data and insufficient understanding regarding the metabolism and actions of P in implantation and pregnancy maintenance. In the present review, we discuss how different P assay methodologies affect the determination of P thresholds for implantation and pregnancy maintenance. In addition, we discuss the importance of free P and its regulation in the endometrium and show the complexity of molecular signaling that is required for P-dependent endometrial receptivity. We concluded that future studies should focus on defining accurate circulating and endometrial P concentrations, both for total and free P, and how these concentrations correlate with endometrial receptivity and clinical outcomes.
- Published
- 2024
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