Our investigations are the first to link the critical role of GLUT4 in the endometrial epithelium glucose uptake and transport to the uterine fluid glucose concentration and endometrial receptivity during early pregnancy, which may provide new clues for understanding the pathogenesis of infertility, such as PCOS, endometrial cancer, and early miscarriage. Here, SLC2A4 is linked to polycystic ovary syndrome.