Evidence of impaired endometrial receptivity after ovarian stimulation for in vitro fertilization: a prospective randomized trial comparing fresh and frozen-thawed embryo transfers in high responders.

Clinical pregnancy rates of 80% and 65% were observed in cycles using thawed and fresh embryos, respectively, although embryo quality indicators revealed morphologically and numerically inferior embryo cohorts after cryopreservation. Subsequent logistic regression analysis controlled for differences in embryo quality and revealed significantly greater probability of clinical pregnancy with thawed embryos when compared with fresh, suggesting a negative effect of ovarian stimulation on endometrial receptivity.