Factors Influencing Oocyte Yield and Embryo Quality in Donor IVF Cycles: A Retrospective Cohort Study

Pin-Yao Lin^1,2,3*Chun-I Lee Lee^1,3,4Hsiu-Hui Chen^1,3Chun-Chia Huang^1,3Ming-Jer Chen^1,5,6Tzu-Ning Yu¹Tsung-Hsien Lee^1,4,7Maw-Sheng Lee^1,4,7*

• ¹Lee Women's Hospital, Taichung, Taiwan
• ²Taiwan IVF Centers Lee Women's Hospital, Taichung, Taiwan
• ³National Chung Hsing University Department of Post-Baccalaureate Medicine, Taichung, Taiwan
• ⁴Chung Shan Medical University Hospital, Taichung, Taiwan
• ⁵Taichung Veterans General Hospital, Taichung, Taiwan
• ⁶National Yang Ming Chiao Tung University, Hsinchu, Taiwan
• ⁷Chung Shan Medical University, Taichung, Taiwan

Background: Achieving an optimal balance between oocyte yield and embryo quality is central to donor IVF. Although anti-Müllerian hormone (AMH) predicts oocyte quantity, donor characteristics and stimulation parameters may influence embryo developmental competence. We aimed to identify clinical and protocol-related factors associated with oocyte yield and embryo quality in a large donor cohort. Methods: We retrospectively analyzed 584 donor IVF cycles at a single center (Jan 1, 2018–Dec 31, 2023). Donor variables included age, AMH, BMI (body mass index), and baseline hormones. Stimulation used gonadotropin-releasing hormone (GnRH) antagonist (27.1%) or progestin-primed ovarian stimulation (PPOS)(72.9%); recombinant human luteinizing hormone (LH) was used in 86% of cycles; final maturation was GnRH agonist (GnRHa) (59.4%) or dual trigger (40.6%). Outcomes were oocyte yield and embryo quality metrics (maturation, two-pronuclear (2PN) fertilization, Day 3 good-quality embryo rate, blastocyst formation rate, and top-quality blastocyst rate). Multivariable linear regression and propensity score matching (PSM) compared protocols and LH supplementation. Results: Donors were 25.6 ± 3.7 years with AMH 6.1 ± 2.9 ng/mL and BMI 21.6 ± 2.8 kg/m². Per cycle: 27.1 ± 11.1 oocytes, 20.8 ± 8.3 MII (maturation 78.2 ± 13.4%), 2PN fertilization 73 ± 18%, Day 3 good-quality embryos 10.6 ± 6.0 (69.5 ± 23.5%), blastocysts 9.5 ± 5.5 (56.7 ± 22.5%), and top-quality blastocysts 6.1 ± 4.2 (36.5 ± 20.1%). First transfers (n=491) yielded 55.4% clinical pregnancy and 44.4% live birth; miscarriage 12.2%. AMH independently predicted oocyte number; higher BMI was associated with lower fertilization. PPOS produced lower Day 3 good-quality embryo (67.9% vs 72.8%) and top-quality blastocyst rates (59.7% vs 74.1%) versus antagonist in PSM, with similar blastocyst formation rate (64.0% vs 60.9%). LH supplementation modestly increased fertilization (74.4% vs 69.5%) without downstream differences. Dual trigger was associated with reduced blastocyst formation rate but a higher proportion of top-quality blastocysts. Conclusions: In donor IVF, AMH is the principal predictor of oocyte yield, whereas BMI, stimulation protocol, and trigger method influence embryo quality. Despite protocol-dependent morphology differences, pregnancy and live birth rates remained high. Findings support individualized stimulation strategies that consider donor profile and protocol effects to optimize efficiency and outcomes.