Received October 23, 2025
Accepted October 24, 2025

Design: Retrospective observational study that included only single embryo transfers (SET) of thawed day 5 or 6 good morphology blastocysts with PGT-A (January 2022–May 2024). Patients were divided into natural or artificial endometrial preparation groups, each with three subgroups based on progesterone support (oral dydrogesterone, vaginal micronized progesterone, or both). Exclusion criteria included submucosal fibroids, endometrial polyps, intramural fibroids ≥5 cm, and hydrosalpinx on transvaginal ultrasound. Results: The reported odds ratios (OR), confidence intervals (CI), and p-values indicate improved clinical pregnancy (0.37 [0.13–1.02], p = 0.047) and live birth (0.46 [0.24–0.89], p = 0.022) outcomes in the natural cycle group, alongside a higher miscarriage incidence (2.96 [1.51–5.96], p = 0.002) in the artificial preparation group. GLM were also applied across six subgroups for these outcomes. A statistically significant advantage in clinical pregnancy was observed in the natural cycle group using oral progesterone. Conversely, a higher miscarriage incidence occurred in the artificial cycle group using oral progesterone compared to the natural cycle group with the same progesterone type. Regarding neonatal birth weight, artificial preparation cycles showed an average weight gain of 135.81 grams, though not statistically significant (135.81 [-138.29 –118-409.90], p = 0.326). Gestational complications, including gestational diabetes, preeclampsia, and HELLP syndrome were evaluated using the z test, showing significant difference between groups in respect to gestacional diabetes (z 2.156, p = 0.03).