The ERA test of endometrial receptivity determines when is the best time for implantation.
The different phases through which the endometrium passes are regulated by the expression of a series of specific genes, and endometrial receptivity studies try to find out which genes are active in the implantation window.
For the ERA test, an endometrial biopsy is needed on the days we think are the implantation window, and the genes that are being expressed are compared with a pattern that is expressed in the implantation window of fertile women.
Sometimes the window of implantation is shifted and the best time to perform the embryo transfer is not 5 days after the ovarian puncture, but at another time. The ERA test is a tool that allows calculating the best moment for the transfer of the embryos in a personalized way for each woman, in order to try to coordinate the embryo quality with the best endometrial environment that can facilitate implantation and pregnancy.