A specialized, enlarged, connective tissue cell of the decidua with enlarged nucleus, dense membrane‐bound secretory granules and cytoplasmic accumulation of glycogen and lipid droplets. These cells develop by the transformation of endometrial stromal cells during decidualization. [ http://www.ncbi.nlm.nih.gov/pubmed/30429548 http://purl.obolibrary.org/obo/BTO_0002770 http://www.ncbi.nlm.nih.gov/pubmed/30013421 ]