PTGS2 and abortion: In a spontaneous abortion-prone mouse model, intraperitoneal injection of FBP increased FBP levels in both uterus and plasma and induced a high percentage of cyclooxygenase-2 (COX-2) + M2-like macrophages, regulatory T cells (Tregs), and T helper 2 (Th2) cells, which improved decidualization and trophoblast invasion (39).