The prognostic value of the Oocyte Maturation Index (OMI) on pregnancy outcomes in POSEIDON group 3 and 4 patients: a retrospective cohort study

BACKGROUND: This study METHODS: A total of 662 patients treated at the Assisted Reproductive Techniques Unit of Mersin University Faculty of Medicine between 2016 and 2024 (Group 3: n=245; Group 4: n=417) were retrospectively analyzed. Patients were divided into three subgroups based on OMI values: ≤50%, 51-75%, and >75%. RESULTS: In both POSEIDON groups, the numbers of aspirated follicles, retrieved oocytes, MII oocytes, and high-quality day-3 embryos showed significant differences between OMI groups (p<0.001). In POSEIDON Group 3, patients with an OMI of 51-75% achieved the highest rates of biobiochemical pregnancy (43.9%), clinical pregnancy (42.1%), and live birth (35.1%), while these rates were lowest in the group with an OMI of ≤50% (10.9%, 10.9%, and 5.5%, respectively; p=0.001). In POSEIDON Group 4, while OMI significantly influenced chemical (p=0.005) and clinical pregnancy (p=0.014) rates, it did not result in a statistically significant difference in live birth rates (p=0.056). CONCLUSION: OMI is a clinically significant prognostic parameter, particularly for younger patients in the POSEIDON Group 3. In older patients (Group 4), however, age-related oocyte proglems my controbite the decisive effect of OMI on live birth. Incorporating OMI into routine clinical evaluations may contribute to personalized treatment planning and patient counseling.