The purpose of this study is to determine whether endometrial receptivity markers obtained by endometrial sampling are effective in prediction of in vivo human embryo implantation.

Since the introduction of In vitro fertilization (IVF), substantial improvements have been developed in ovulation induction, oocyte retrieval, fertilization capability and embryonic development. However, the end point which is to improve implantation and pregnancy rates after transferring embryos, remains below physiological expectations. It has been estimated that clinical implantation in the human is efficient in no more than 30% of cases considering that only one embryo is present in natural cycles, which gives us a 30% implantation rate.

A frequent pitfall found in the literature is the consideration that implantation is the result of good embryonic quality. Although this is completely true, it is not the only truth because the maternal endometrium is at least of equal relevance. In ovum donation, the endometrial factor could also be improved by individualizing the implantation window in each patient. In this proposed research we will analyze suggested markers of endometrial receptivity in order to optimize human implantation in patients undergoing assisted reproductive technologies focusing on improving endometrial receptivity in IVF and ovum donation patients.

Inclusion Criteria:

• Patients scheduled for IVF or OD

Exclusion Criteria:

• Cervical stenosis