evidence: No statistically significant differences were observed in PR (43.1 % vs. 48.7 %, respectively), LBR (28.7 % vs. 35.0 %, respectively), and MR (4.4 % vs. 5.9 %, respectively) after injection with hCG vs. medium.
intervention: cohort A, hCG application was performed two days before blastocyst transfer, 
comparator: cohort B, the administration of hCG occurred just prior to embryo transfer on day 5
outcome: pregnancy rates (PR), clinical pregnancy rates (cPR), miscarriage rates (MR), and live birth rates (LBR)