IL1R1 and endometriosis: There are caveats for using IL-1/IL-1R1 blocking reagents to treat patients with endometriosis wishing to give birth, such as the reported IL-1R antagonist (IL-1Ra)-induced inhibition of murine embryo implantation in vivo, and of increased trophoblast motility by urokinase plasminogen activator and plasminogen activator inhibitors in vitro (42, 43).