Following oocyte retrieval, collected oocytes will be incubated in Global Total for Fertilization within a K-Systems incubator until the time of denudation and intracytoplasmic sperm injection (ICSI). All mature (MII) oocytes will undergo ICSI at 39-41 hours post-trigger. After insemination, sibling oocytes will be divided as equally as possible and randomly allocated into two separate Geri incubator chambers: Group 1 will be cultured in the dry chamber, and Group 2 will be cultured in the humidified chamber. A predefined randomization list will determine allocation, including cases with an uneven number of oocytes, where the additional oocyte will be assigned according to the list. Both groups will use Global TotalR (GT, CooperSurgical) single-step medium. Embryo culture will be carried out in continuous culture conditions until the blastocyst stage, following the manufacturer's GT protocol, with no Day 3 media refreshment. To minimize procedural variability, one operator will ideally

Day 5 blastulation versus total blastulation refers to comparing the proportion of embryos that reach the blastocyst stage specifically by Day 5 against the overall number of embryos that eventually form blastocysts

Blastocyst quality at the time of biopsy will be assessed using the modified Gardner's grading system, which evaluates three key components of the blastocyst: the degree of expansion, the quality of the inner cell mass (ICM), and the quality of the trophectoderm (TE). This standardized scoring allows objective comparison of embryo morphology and developmental competence at the moment of trophectoderm biopsy.

Total blastulation rates per MII and per 2PN refer to the proportion of inseminated mature oocytes (MII) and normally fertilized zygotes (2PN) that successfully develop into blastocysts, regardless of whether they reach this stage on Day 5 or Day 6. This measurement reflects the overall efficiency of embryo development from both the point of maturation and normal fertilization.