COL1A1 is regulated at the epigenetic, transcriptional, post‐transcriptional, and post‐translational levels including DNA methyl transferases (DNMTs), TGFβ, terminal nucleotidyltransferase 5A (TENT5A), or glucose‐regulated protein (Grp78).[43] Previous studies have found that HF can inhibit the phosphorylation of STAT3, and p‐STAT3 may regulate transcription of COL1A1.[44, 45] We also observed that HF could inhibit the expression of p‐STAT3 and the activation of TGFβ1/2 in CAF1 and CAF2 (Figure S11, Supporting Information). This evidence concerns the gene STAT3 and hydrops fetalis.