These results cooperatively suggest that the overexpression of proMBP in the IUGR-twin of sIUGR would suppress the PAPP-A activity and impair EVT implantation, therefore resulting in the imbalanced growth of sIUGR twins, highlighting the significance of proMBP regulation of PAPP-A proteolysis on placental function. The gene discussed is PAPPA; the disease is fetal growth restriction.