The interaction between fibroblasts and T cells was confirmed to be mediated by the ligand‐receptor pair of CXCL12‐CXCR4 and to trigger the differentiation of Treg cells, as CXCL12 signaling possessed the ability to stimulate T cell chemotaxis and gene expression via its receptor CXCR4.[56] The origin of all events observed in females suffering from IUGR might be attributed to the elevated level of E2. This evidence concerns the gene CXCL12 and fetal growth restriction.