Fixed vs Flexible PPOS

we compared embryo euploidy outcomes between fixed and flexible PPOS in a large PGT-A cohort. To the best of our knowledge, this is the first study to evaluate progestin-initiation timing in a PGT-A–only population, minimizing confounding from unrecognized aneuploid embryos. We also assessed clinical outcomes, including clinical pregnancy and live birth, to determine whether differences in exposure duration translate into clinically meaningful effects.