Markers of ER stress, such as phosphorylated protein kinase R (PKR)-like endoplasmic reticulum kinase (p-PERK), phosphorylated Eukaryotic translation initiation factor 2A (p-eIF2α), phosphorylated Inositol-requiring enzyme 1 (p-IRE1α), immunoglobulin heavy chain-binding protein (BiP), and C/EBP Homologous Protein (CHOP), were found to be upregulated in mouse embryonic hearts exposed to maternal hyperglycemia compared with those exposed to control glycemic conditions [113,116]. This evidence concerns the gene ERN1 and Hyperglycemia.