Early embryo cleavage and day 2 mononucleation after intracytoplasmatic sperm injection for predicting embryo implantation potential in single embryo transfer cycles.

In this study we analyzed the outcome of 275 fresh single embryo transfer cycles of day 2, mononucleate four-cell preembryos that had either cleaved early (n = 175) or not cleaved early (n = 100) 25 to 28 hours after intracytoplasmatic sperm injection. Neither the implantation rate nor the delivery rate showed any difference between the two groups, indicating that when a top-quality preembryo (mononucleate four-cell preembryo on day 2) is transferred, the presence of early cleavage seems to add no additional advantage in predicting the implantation potential of the preembryo.