Association of HDL-cholesterol related inflammatory ratios with reproductive outcomes in women with polycystic ovary syndrome undergoing frozen-thawed embryo transfer

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder and a major cause of anovulatory infertility, often requiring assisted reproductive technology (ART). The freeze-all strategy followed by frozen-thawed embryo transfer (FET) can reduce the risk of ovarian hyperstimulation syndrome (OHSS) and improve endometrial receptivity. However, women with PCOS still experience suboptimal reproductive outcomes. Increasing evidence suggests that chronic low-grade inflammation may contribute to these impairments. Conventional inflammatory markers, such as circulating cytokines, are not routinely assessed in clinical practice, underscoring the need for simple and accessible indicators. Recently, several hematologic and lipid-based inflammatory ratios—lymphocyte-to-HDL cholesterol ratio (LHR), neutrophil-to-HDL cholesterol ratio (NHR), platelet-to-HDL cholesterol ratio (PHR) and monocyte-to-HDL cholesterol ratio (MHR)—have been proposed as accessible indicators of systemic inflammation. Nevertheless, their predictive value for ART outcomes in women with PCOS remains unclear. This retrospective cohort study included 1445 women with PCOS undergoing their first frozen embryo transfer cycle at the reproductive medicine center of a tertiary hospital between 2010 and 2023. The associations of reproductive outcomes with NHR, LHR, PHR and MHR were assessed using logistic regression models with or without adjusting for potential confounders. Higher quartiles of NHR, LHR, and PHR were associated with increased miscarriage rates and decreased live birth rates, whereas no consistent pattern was observed for MHR. No significant differences were found across quartiles in biochemical pregnancy, clinical pregnancy, preterm delivery and low birth weight. Compared with women in the lowest quartile, those in the highest quartile had significantly higher odds of miscarriage for NHR (adjusted odds ratio [OR] 2.51, 95% confidence interval [CI] 1.39–4.63), LHR (2.32, 1.23–4.49) and PHR (2.47, 1.34–4.64). In addition, LHR and PHR were inversely associated with live birth after full adjustment. Elevated NHR, LHR, and PHR were associated with adverse reproductive outcomes in women with PCOS undergoing FET. These findings suggest that HDL-C related inflammatory ratios may have potential value as accessible markers of systemic inflammation in this population. However, given the retrospective design, their clinical utility for risk stratification and individualized management requires further validation in prospective studies. Not applicable.