CD38 and fetal growth restriction: In this study, compared with the NBW group, abnormal expression of NAD +-consuming enzymes (CD38, SIRT4, BST1, and NNMT) and calcium signaling-related genes (CAMK1D, CAMK1, CALML4, CACNB1, and CACNB3), as well as altered concentrations of NAD+, N-methyl-2-pyridone-5-carboxamide, and cADPR were observed in the IUGR group.