Study on the Association Between the Systemic Immune-Inflammation Index and Polycystic Ovary Syndrome in Women Undergoing in vitro Fertilization for Subfertility

Polycystic ovary syndrome (PCOS) is closely associated with chronic low-grade inflammation. Systemic immune-inflammation index (SII) based on complete blood cell count has shown superior discriminative value in a variety of diseases, but its role in PCOS is still unclear. This study aimed to investigate the association between SII and PCOS in women undergoing their first in vitro fertilization (IVF) treatment with a gonadotropin-releasing hormone (GnRH) antagonist protocol.

A total of 334 women undergoing their first IVF treatment with a GnRH antagonist protocol from January 2019 to December 2025 were included in this study. They were divided into the PCOS group (n=160) and the non-PCOS group (n=174). Demographic and physical indicators, reproductive endocrine indicators, systemic inflammatory indicators, infertility situation, ovulation induction treatment parameters, and trigger day indicators were collected. Binary logistic regression was used to identify the independent associated factors of PCOS.

The results of the multivariate analysis indicated that anti-Mullerian hormone (AMH) (OR=1.437, 95% CI: 1.222-1.690, P<0.001), basal follicle-stimulating hormone (FSH) (OR=0.718, 95% CI: 0.519-0.993, P=0.046), luteinising hormone (LH) (OR=1.293, 95% CI: 1.100-1.519, P=0.002), testosterone (T) (OR=14.533, 95% CI: 2.162-97.677, P=0.006), SII (OR=2.030, 95% CI: 1.079-3.819, P=0.028), and LH level on the trigger day (OR=1.284, 95% CI: 1.061-1.554, P=0.010) were independently associated with PCOS.

Among patients undergoing their first IVF treatment, SII was independently associated with PCOS. This further supported the crucial role of chronic low-grade inflammation in the pathophysiology of PCOS. In the future, its efficacy needs to be verified through large-scale studies. Before it is fully confirmed, it is not recommended to use it as an independent clinical tool.