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

In vitro fertilization outcomes may be improved by performing frozen instead of fresh embryo transfer. These results could be explained by avoiding the deleterious effects of controlled ovarian hyperstimulation on endometrial receptivity.


Matheus Roque, M.D., Karinna Lattes, M.D., Sandra Serra, M.Sc., Ivan Solá, B.Psych., Selmo Geber, Ph.D., Ramón Carreras, Ph.D., Miguel Angel Checa, Ph.D.

Volume 99, Issue 1, Pages 156-162, January 2013



To examine the available evidence to assess if cryopreservation of all embryos and subsequent frozen embryo transfer results in better outcomes compared with fresh transfer.


Systematic review and meta-analysis.


Centers for reproductive care.


Infertility patient(s).


An exhaustive electronic literature search in MEDLINE, EMBASE and The Cochrane Library was performed until December 2011. We included randomized clinical trials comparing outcomes of IVF cycles between fresh and frozen embryo transfer.

Main Outcome Measure(s):

The outcomes of interest were ongoing pregnancy rate, clinical pregnancy rate, and miscarriage.


We included three trials accounting for 633 cycles in women aged 27 to 33 years. Data analysis showed that FET resulted in significant higher ongoing pregnancy rates(RR = 1.32, 95% CI 1.10 – 1.59) and clinical pregnancy rates (RR = 1.31, 95% CI 1.07 –1.52).


Our results suggest that there is evidence that IVF outcomes may be improvedby performing FET compared to fresh embryo transfer. This could be explained by a betterembryo-endometrium synchrony achieved with endometrium preparation cycles.

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