What is recurrent implantation failure? This means that in spite of putting good quality embryos into the uterine cavity, success in terms of pregnancy has not been achieved in IVF. One of the most important factors for this is poor endometrial receptivity. This can be assessed by doing a test called Endometrial receptivity assay or ERA. This tells us about the correct implantation window so that our embryo transfers can be modified accordingly. If a transfer fails even after correction of endometrial receptivity, stress needs to be ruled out.