Reduced live birth rates in frozen versus fresh single cleavage stage embryo transfer cycles: A cross -sectional study.

Background: Studies have suggested that embryo-endometrial developmental asynchrony caused by slow-growing embryos can be corrected by freezing the embryo and transferring it back in a subsequent cycle. Therefore, we hypothesized that live birth rates (LBR) would be higher in frozen embryo transfer (FET) compared with fresh embryo transfers.

Objective: To compare LBR between fresh and FET cycles.