Introduction. Implantation failure appears to be a significant factor in Assisted reproductive technique (ART) procedures. Even a mature endometrium may be non-receptive, preventing implantation or rejection of implanted embryo in early months of pregnancy, resulting in miscarriage or unexplained infertility with or without other associated factors. Objective. To investigate causes of failed implantation inspite of uneventful Grade I embryo transfer in ART procedure Material and Method. 90 women aged range between 25-40 yr old who visited Department of Reproductive Medicine at Calcutta Fertility Mission, over a period of 24 months(January 2017 to December 2019) , satisfying the inclusion criteria, were enrolled in this observational study. Endometrial aspirate histopathology was done along with ∞5β3 integrin expression. They were treated with natural micronized progesterone (NMP) or oral dydrogesterone and results of endometrial changes were statistically analyzed. Results. 28.89% and 31.11% of women were seen to have mid-secretory changes of the endometrium after being treated with NMP and dydrogesterone respectively. Integrins were expressed in only 59.26% of women with mid-secretory endometrium and 5.41% of early secretory endometrium, which was statistically significant (p value <0.001). Conclusion. About 70% patients even after treatment with estrogen and progestin did not have adequate response in endometrial maturation. Not all patients with mid-secretory endometrium had integrin positive, when tested. NMP and oral Dydrogesterone have similar effect in endometrial maturation as well as in yielding successful pregnancy in some patients with previously failed In-vitro fertilization embryo transfer (IVF-ET).