Diagnostic Test for Endometrial Receptivity 24 Hours Before Embryo Transfer

Inclusion Criteria: * Any IVF patient being treated for single or double embryo transfer * BMI: 20 - 30 * Normal ovarian response (7 - 8 ovocitos) in IVF treatment with AFC ≥ 8, (AFC = Antral Follicle Count) * Elective embryo transfer * Normal uterine cavity * Age: ≤ 38 years old for patients with own oocytes; ≤ 50 years old for patients with donated oocytes. Exclusion Criteria: * Patients with recurrent miscarriages ( ≥ 2 biochemical miscarriages; ≥ 2 clinical miscarriage) * Patients with severe male factor ( ≥ 2\*106 espermatozoides/ml).