Abstract
INTRODUCTION: Polycystic ovary syndrome (PCOS) presents with heterogeneous phenotypes that may influence reproductive outcomes in assisted reproductive treatment. To compare oocyte and embryo quality in PCOS patients with regular versus irregular menstrual cycles undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) using a uniform stimulation protocol. MATERIAL AND METHODS: This retrospective cohort study was conducted at an infertility clinic in Lahore, Pakistan, over 12 months (January-December 2024). PCOS patients aged 25-39 years undergoing their first IVF/ICSI cycle with a short antagonist protocol were included and stratified into regular and irregular cycle groups. Baseline characteristics, stimulation response, oocyte yield, fertilization and cleavage rates, and blastocyst-stage development were compared. RESULTS: A total of 50 patients met the inclusion criteria (19 regular cycle, 31 irregular cycle). Irregular cycle patients required higher gonadotropin doses and exhibited greater hormonal dysregulation. Although oocyte maturation was higher in the irregular group, blastocyst-stage embryo development was more frequent in the regular cycle group, indicating superior downstream competence. Fertilization and cleavage outcomes were comparable between groups. CONCLUSION: Menstrual irregularity in PCOS is associated with a less favorable embryo development profile despite similar initial fertilization kinetics. PCOS patients with regular menstrual cycles exhibited a higher yield of advanced-stage embryos, suggesting a milder reproductive phenotype.