TNF and Dysmenorrhea: In the sensitivity analyses excluding those who had taken steroid medications within the 48 h prior to the blood draw, the association between dysmenorrhea severity and IL-6 among the controls was attenuated, while the association between dysmenorrhea severity and TNF-α as well as that between dysmenorrhea frequency and IL-1β and IL-6 (Tables S7 and S8) changed negligibly.