We examined IAIR, and the frequency of intra-amniotic inflammation (IAI) and EONS according to the progression of inflammation in CP [i.e., stage-0, inflammation-free CP; stage-1, inflammation restricted to subchorionic fibrin (SCF); stage-2, inflammation in connective tissue (CT) of CP but without chorionic vasculitis; and stage-3, chorionic vasculitis]. This evidence concerns the gene KITLG and inflammatory response.