Transfer of early-cleaved embryos increases implantation rate in patients undergoing ovarian stimulation and ICSI-embryo transfer.

The hypothesis that inspection for early cleavage improves pregnancy rate by aiding selection of the best embryos for transfer was tested in this study. Inspection for early cleavage was performed randomly in women undergoing intracytoplasmic sperm injection (ICSI) cycles. No differences were observed between early cleavage-inspected and uninspected embryos. When the hypothesis that transfer of early-cleaved (EC) embryos yields a higher pregnancy rate than transfer of late-cleaved (LC) embryos was tested using early cleavage-inspected cycles, it was found that transfer of EC embryos resulted in a higher implantation rate than transfer of LC embryos. In transfers for which all embryos were EC (100% EC), transfer of fewer embryos yielded a higher implantation rate compared with LC and uninspected cycles. These results indicate that, when inspected, early cleavage increases the implantation rate in ICSI patients.