Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: a systematic review and meta-analysis

Objective: To examine the available evidence to assess if cryopreservation of all embryos and subsequent frozen embryo transfer (FET) results in better outcomes compared with fresh transfer. Design: Systematic review and meta-analysis. Setting: Centers for reproductive care. Patient(s): Infertility patient(s). Intervention(s): An exhaustive electronic literature search in MEDLINE, EMBASE, and the Cochrane Library was performed through December 2011. We included randomized clinical trials comparing outcomes of IVF cycles between fresh and frozen embryo transfers. Main Outcome Measure(s): The outcomes of interest were ongoing pregnancy rate, clinical pregnancy rate, and miscarriage. Result(s): We included three trials accounting for 633 cycles in women aged 27-33 years. Data analysis showed that FET resulted in significantly higher ongoing pregnancy rates and clinical pregnancy rates. Conclusion(s): Our results suggest that there is evidence that IVF outcomes may be improved by performing FET compared with fresh embryo transfer. This could be explained by a better embryo-endometrium synchrony achieved with endometrium preparation cycles. (Fertil Steril (R) 2013;99:156-62. (C) 2013 by American Society for Reproductive Medicine.)