In animal studies, quercetin has been shown to modulate the immune microenvironment at the maternal–fetal interface, leading to a decrease in the ratio of CD4+/CD8+ T cells and IFN-γ/IL-4 in the decidua tissue of LPS-induced pregnant mice, which resulted in a decreased rate of embryo resorption and reduced incidence of miscarriage (Wang et al., 2011). This evidence concerns the gene CD4 and spontaneous abortion.