Insulin resistance as a determinant of fertilization efficiency in polycystic ovary syndrome patients undergoing IVF/ICSI: a retrospective cohort study.

Background: This retrospective cohort study aimed to evaluate the impact of insulin resistance (IR) on clinical outcomes in polycystic ovary syndrome (PCOS) patients undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment.

Methods: A total of 1,768 PCOS patients undergoing IVF/ICSI cycles at Shenzhen Zhongshan Obstetrics & Gynecology Hospital between October 2010 and November 2024 were stratified into two cohorts: non-IR group (HOMA index < 2.69, n = 867) and IR group (HOMA index ≥ 2.69, n = 901). Baseline characteristics and clinical outcomes were compared between the groups. Linear logistic regression and multivariate logistic regression analysis were conducted to assess the independent impact of IR on fertilization efficiency and pregnancy outcomes.

Results: Patients with IR exhibited significantly higher BMI (25.44 ± 3.55 vs. 21.59 ± 3.20, p < 0.001), longer infertility duration (3.74 ± 2.75 vs. 3.25 ± 2.43, p < 0.001), increased antral follicle counts (26.74 ± 10.74 vs. 25.05 ± 9.79, p < 0.001) and lower basal follicle-stimulating hormone (FSH) level (9.78 ± 3.25 vs. 10.64 ± 3.83, p < 0.001) compared to those without IR. Additionally, the fertilization rate (82.02% vs. 83.86%, p = 0.005) and 2PN rate (81.07% vs. 83.96%, p < 0.001) were significantly lower in PCOS patients with IR. Linear regression indicated that IR had a more pronounced inverse effect on 2PN rate (B: -2.540, p = 0.009) than on fertilization rate (B: -0.664, p = 0.490). Subgroup analysis and interaction analysis demonstrated that IR functioned as an independent risk factor for impaired oocyte fertilization in normal-weight PCOS patients (B: -22.694, p = 0.011). No statistically significant associations between IR status and clinical or live birth pregnancy outcomes were observed in the regression models.

Conclusions: IR adversely affects oocyte fertilization competence and early embryonic development in normal-weight PCOS patients undergoing assisted reproductive technology (ART). These effects may be attributable to IR-induced metabolic dysregulation, which compromises folliculogenic and cytoplasmic maturation processes critical to gamete competence. These findings underscore the importance of addressing metabolic dysfunction in IR-affected PCOS populations to optimize ART outcomes.

Trial registration: This is a retrospective study.