Frozen embryo transfers: implications of clinical and embryological factors on the pregnancy outcome.

Background: Frozen embryo transfers are characterized by impaired pregnancy outcome and increased incidence of pregnancy loss as compared with fresh IVF/ICSI embryo transfers. In this study, we performed a retrospective analysis of clinical and embryological factors that potentially influence the outcome of frozen embryo transfer.

Methods: We reviewed the outcome of 1242 frozen embryo transfers with respect to the age of the woman, the method of fertilization, embryo quality before and after freezing and the number of embryos transferred.