The ERA Test as a Diagnostic Guide for Personalized Embryo Transfer

Inclusion Criteria: 1. Patients indicated to undergo a cycle of IVF/ICSI with their own oocytes. 2. Age ≤ 37 years 3. BMI: 18.5 to 30 4. Normal ovarian reserve (AFC ≥ 8; FSH \< 8) 5. The most appropriated stimulation protocol will be decided by their doctor. 6. Blastocyst transfer (on day 5 or 6) 7. Blastocyst vitrification with open protocols (Cryotop, Cryoleaf, or Cryolock) or closed protocols (Cryotip or CBSStraw.) 8. Any pathology affecting the endometrial cavity such as polyps/sub-mucosal myomas, intramural myomas \> 4 cm, or hydrosalpinx affecting the endometrial cavity must be previously operated. Exclusion Criteria: 1. Patients with recurrent miscarriages (\> 2 previous biochemical pregnancies or \> 2 spontaneous miscarriages) 2. Patients with a severe male factor (spermatozoa \< 2 million/ml) 3. Patients with implantation failure (\>3 failed cycles with good quality embryos) Post-Randomization Exclusion Criteria: 1. Endogenous progesterone level ≥ 1,5 ng/ml at the day of hCG administration in all groups. 2. Absence of blastocysts (day 5 or 6) for embryo transfer. 3. Risk of ovarian hyperstimulation syndrome in any of the three groups and therefore a clinical indication to cancel the transfer cycle where the stimulated patient is from group A (ET). Note: PGT-A is not an inclusion criteria neither an exclusion criteria, therefore those cycles in which PGT-A was performed will be included