In vitro fertilization with personalized blastocyst transfer versus frozen or fresh blastocyst transfer: a multicenter, randomized clinical trial.

Objective: To determine the effectiveness of personalized embryo transfer (pET) versus frozen embryo transfer (FET) or fresh embryo transfer (ET) in infertile patients undergoing IVF at their first appointment. In pET, embryo transfer is performed within the optimal window of implantation identified by the endometrial receptivity analysis (ERA). Design(s): Multicenter randomized clinical trial. Participants aged <= 37 years scheduled for IVF with elective blastocyst transfer at the first appointment were randomized to undergo pET, FET or ET. Material(s) and Method(s): Setting: 16 reproductive medicine centers in Europe, America and Asia with a common reference genetic laboratory. Patient(s): We recruited 569 women, and 458 were randomly assigned to pET (N=148), FET (N=154), or ET (N=156) groups. Intervention(s): The ERA test was performed using hormone replacement therapy guiding embryo transfer in the pET arm. Blastocyst vitrification was performed in the pET and FET arms. Blastocyst transfer in all groups. Main outcome measure(s): The primary outcome was live birth. Secondary outcomes were pregnancy and implantation rates as well as clinical miscarriage, biochemical pregnancy, and obstetric and neonatal outcomes. We performed intention-to-treat and per protocol analyses. Result(s): In the per protocol analysis, live birth rates at the first embryo transfer were 45 of 80 (56.2%) in the pET group, 39 of 92 (42.4%) in the FET group, and 43 of 94 (45.7%) in the ET group (pET versus FET relative risk [RR] 1.35, 95% confidence interval (CI) 0.97- 1.86; p=0.09; pET versus ET [RR] 1.26, 95% (CI) 0.91-1.74; p=0.17). Cumulative live birth rates after 12 months were 57 of 80 (71.2%) in the pET group, 51 of 92 (55.4%) in the FET group, and 46 of 94 (48.9%) in the ET group (pET versus FET [RR] 1.47, 95% (CI)1.01-2.13; p=0.04; PET versus ET [RR]1.71, 95% (CI) 1.17-2.49; p=0.003). Pregnancy rates at the first embryo transfer in the pET, FET and ET were 72.5%, 54.3% and 58.5% res