Hernandez-Nieto C, Lee JA, Alkon-Meadows T, et al. - Researchers investigated the influence of a late follicular phase progesterone elevation (LFPE) during controlled ovarian hyperstimulation (COH) on embryonic competence and reproductive potential in thaw cycles of preimplantation genetic testing for aneuploidy (PGT-A) screened embryos. They performed a retrospective cohort analysis in a single, academic ART center. Among a total 5,244 analyzed COH cycles for IVF/PGT-A, 5,141 were included in the analysis. Trophectoderm biopsy and PGT analysis were performed on a total of 23,991 blastocysts. In addition evaluation was done on the clinical IVF outcomes of 5,806 single euploid FET cycles. Separation of the cohorts was done as follows: Group 1: oocytes retrieved from cycles with normal P levels during ovulation trigger (P ≤ 2.0 ng/ml); Group 2: oocytes retrieved after cycles in which LFPE was noted (P > 2.0 ng/ml). They performed comparison of 4,925 cycles in Group 1 with 216 cycles on Group 2. The groups were comparable concerning oocyte maturity rates, fertilization rates and blastulation rates. Per findings, LFPE with a progesterone cutoff value of 2.0 ng/ml is not linked with impaired embryonic development, increased rate of embryonic aneuploidy, as well as not with compromised implantation and pregnancy outcomes following a euploid frozen embryo transfer (FET) cycle.