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.

  • matheus_roque

    As the authors of this systematic review and meta-analysis that compared the
    results between fresh embryo transfer and elective frozen–thawed embryo
    transfer (eFET), we reviewed the manuscript as it was found that the study by
    Aflatoonian et al. 2010 was retracted after the publication of our study.
    We performed another analysis excluding the aforementioned study. The analysis of
    the available data also showed that eFET resulted in a statistically
    significant increase in the clinical pregnancy rate compared to the rate
    observed with fresh embryo transfer (RR=1.28, 95% confidence interval [CI]:
    1.03–1.60; I2=0%). However, when we
    evaluated the ongoing pregnancy rate (OPR), the eFET group showed a higher OPR
    compared to the fresh embryo transfer group, but this difference did not reach
    statistical significance (RR=1.26, 95% CI: 1.00–1.58; I2=0%). This
    new analysis included 259 in vitro fertilization (IVF) cycles in normo and high
    responders following blastocyst embryo transfers

  • Micah Hill

    Thank you for the meta-analysis, which seems very well done. It was interesting to see how similar the results of all 3 RCTs were and how very low (0%) the heterogeneity was across the trials. My only thought is that given 2/3 trials come from the same group, I would love to see more RCTs from other groups where the same results are repeated. Im sure lab quality and experience with vitrification would play major rolls in such outcomes.

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