“…During the GnRH analogue era the term of premature luteinization was nonintentionally dragged from the previous period with the same definition. Although most investigators still apply an absolute P level on hCG day as an indication for elevated P level, the cut-off point has differed considerably between one study and another ranging from 0.9 to 2.0 ng/mL [1,10]. Most recent studies have suggested that a cut-off point of 1.25 [16] or 1.5 ng/mL [2], may differentiate more properly in their detrimental effect on endometrial receptivity, however this should be investigated further taking into account the type of gonadotropin and GnRH analogue (agonist or antagonist) employed.…”