The association between the red blood cell distribution width-to-albumin ratio and female infertility: A cross-sectional study.

Systemic inflammation and oxidative stress play key roles in female infertility. The red cell distribution width-to-albumin ratio (RAR) is a novel biomarker reflecting inflammation and nutritional status, but its association with female infertility remains unclear. This study explores the relationship between RAR and female infertility. Data from the 2013 to 2020 National Health and Nutrition Examination Survey were analyzed. Women aged 20 to 45 years with complete infertility and RAR data were included. Infertility was defined as unsuccessful conception after ≥12 months of attempts. RAR was calculated as red cell distribution width divided by albumin. Weighted logistic regression assessed the association between RAR and infertility, while restricted cubic spline regression examined nonlinear relationships. Subgroup and sensitivity analyses evaluated the robustness of the findings. A total of 4648 women were included. In the fully adjusted model, RAR was positively associated with infertility (odds ratio = 1.29, 95% confidence interval: 1.07-1.54, P = .01), with a significant trend test (P for trend < .05). Restricted cubic spline analysis indicated a primarily linear association (P for nonlinear > .05). Subgroup analyses showed consistent results, and propensity score matching confirmed the robustness of the findings. RAR is positively associated with female infertility, with consistent findings across subgroup and sensitivity analyses. As a biomarker of inflammation and nutritional status, RAR may have potential applications in reproductive health assessment.