CD4 and Infertility: Macrophages play a dual role in both host defense and immune regulation in ETB, while the CD4+/CD8+ T-cell balance is crucial in maintaining reproductive immunotolerance and pathogen clearance (Rao et al., 2015; Scriba et al., 2017; Lv et al., 2023).These immune cell subsets are particularly relevant in reproductive health, as disruptions in their function can lead to implantation failure, recurrent pregnancy loss, and infertility (Gupta and Gupta, 2020).