Preterm birth is the largest single cause of neonatal death and morbidity. By activating cytokine and Toll-like receptor (TLR) signaling pathways, infection and/or inflammation are strongly associated with preterm delivery. Interferon regulatory factor-1 (IRF1) is an important regulator of the inflammatory response. The aims of this study were to establish the effect of (i) labor on IRF1 expression in human fetal membranes and myometrium; (ii) pro-labor mediators on IRF1 expression and activity; and (iii) IRF1 siRNA on the expression of pro-labor mediators. IRF1 expression was higher in fetal membranes and myometrium after spontaneous term labor and in preterm fetal membranes with infection. The pro-inflammatory cytokine IL1B, the bacterial product fsl-1 and viral analogue poly(I:C) significantly increased IRF1 mRNA expression and transcriptional activity in human primary myometrial cells. In addition, IL1B increased IRF1 activity in primary amnion cells. IRF1 silencing in myometrial cells decreased IL1B, fsl-1 and poly(I:C)-induced cytokine (IL6,TNF, IL1B) and chemokine (CXCL8, CCL2) mRNA expression and IL6, CXCL8 and CCL2 release. IL1B, fsl-1 and poly(I:C)-induced PTGS2 mRNA expression and IL1B-induced prostaglandin release was also decreased by IRF1 silencing. In conclusion, IRF1 upregulation in fetal membranes and myometrium after term labor indicates a pro-inflammatory role for IRF1 in human parturition. IRF1 is involved in TLR and cytokine mediated signaling in human myometrium. These data provide new insights into the mechanisms associated with inflammation- and infection-associated preterm birth. IRF1 inhibitors as therapeutics for the management of spontaneous preterm birth warrants further investigation.