Serum progesterone levels are associated with live birth rates in frozen-embryo transfer under artificial preparation. Are progesterone levels affected by other determinants?

Abstract Research Question What factors determine serum progesterone levels the day before frozen embryo transfer (FET) in artificially prepared cycles? Design Retrospective cohort study at a university-affiliated fertility center including infertile women under 45 years old using own oocytes who underwent a total of 685 single frozen blastocyst transfers under hormonal therapy. Determinants that affected live birth rate (LBR) were analyzed using a multivariate logistic regression. Univariate analysis and multivariate linear regression were used to evaluate independent factors that affect serum progesterone levels. Results Age (OR: 0.93 95% CI [0.89-0.96]), duration of estradiol (OR: 0.96 95% CI [0.92-0.99]), serum progesterone levels (OR: 1.04 95% CI [1.01-1.08]) and patients who underwent PGT-A (OR: 2.17 95% CI [1.55-3.03] were independently associated with LBR. After univariate analysis, determinants of progesterone levels were: age, weight, history of a previous FET with serum progesterone levels Conclusion(s) This study adds more evidence regarding the importance of serum progesterone levels before FET. In addition, we demonstrate that body weight, age, time of blood sampling and a history of low progesterone are determinants associated with progesterone levels before blastocyst FET.