IL6 and endometriosis: Regarding dysmenorrhea severity, there was a non-statistically significant suggestion that controls with severe dysmenorrhea had higher levels of IL-6 (geometric mean (GM): 1.64; 95% CI: 1.37–1.97) compared to the controls with no/mild dysmenorrhea (GM: 1.53; 95% CI: 1.43–1.63; p-trend = 0.08), but no association was noted among the endometriosis cases (p-trend = 0.95; Figure 2; Table S3).