PGR and spontaneous abortion: Our study found that SGK1 and its signaling pathway-related proteins (p-Nedd4-2, 14–3-3 protein, ENaC-α), estrogen and progesterone and their receptors (E2, P, ERβ, PR), and decidualization markers (PRL, PRLR, IGFBP-1) were expressed at lower levels in unexplained recurrent miscarriage tissue.