IL18 and female infertility: Using univariable IVW MR analysis in Figure 3, IL-18 levels showed a protective association with female infertility risk (OR: 0.92; 95% CI: 0.86–0.98; P = 1.17 × 10−2), which remained consistent after adjusting for MDD in multivariable IVW MR analysis (OR: 0.93; 95% CI: 0.87–0.99; P = 2.40 × 10−2) in Figure 4.