Endometrial Receptivity Assay (ERA) is a molecular diagnostic test that analyzes gene expression patterns during different phases of the menstrual cycle in an endometrial tissue sample obtained via biopsy. The ERA test is designed to evaluate endometrial receptivity and determine the personalized window of implantation for each patient, therefore synchronizing the embryo transfer with the individualized window of implantation. The ERA test allows the optimal time for an embryo to be transferred into a woman’s uterus for the embryo to implant, known as the window of implantation, to be detected before the patient starts using assisted reproduction techniques. The procedure involves taking a biopsy of the endometrial lining of the uterus and testing the tissue to see which genes are expressed.