Mechanistically, we confirmed that circFBXW4 binds to miR-18b-3p, as a miRNA sponge, to regulate the expression of F box and WD 40 domain containing protein 7 (FBXW7), revealing that the circFBXW4/miR-18b-3p/FBXW7 axis plays crucial roles in HSCs activation and HF. Here, FBXW7 is linked to hydrops fetalis.