Adjusting for IL-18 in the multivariable IVW MR analysis in Figure 4, MDD still exhibited a significant effect on female infertility (OR: 1.19; 95% CI: 1.03–1.38; P = 1.80 × 10−2), with subgroup analyses supporting this causal relationship for infertility linked to cervical, vaginal, other or unspecified origin (OR: 1.18; 95% CI: 1.01–1.38; P = 3.80 × 10−2) and PCOS-linked infertility (OR: 1.20; 95% CI: 1.08–1.33; P = 1.00 × 10−3). Here, IL18 is linked to Infertility.