In addition to chorioamnionitis triggering IL-1 production, i.a. injection of IL-1 was shown to induce sterile chorioamnionitis similar to endotoxins such as LPS: Rhesus macaques were injected with either IL-1β or saline 24 or 72 h before preterm delivery via cesarean section at 80% gestation, i.e., equivalent to 32 weeks GA for a human (8). This evidence concerns the gene IL1A and chorioamnionitis.