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Meta-Analysis
. 2021 May;28(5):1267-1276.
doi: 10.1007/s43032-020-00323-2. Epub 2020 Oct 1.

Pregnancy Outcome Difference between Fresh and Frozen Embryos in Women without Polycystic Ovary Syndrome: a Systematic Review and Meta-Analysis

Xuli Jin  1 , Guangbao Liu  1 , Zhi Jiao  1 , Jiali Sun  2 , Miaomiao Yan  1 , Xiaoyang Lv  1 , Haozheng Zhang  3 , Jie Chen  4
Affiliations
Meta-Analysis

Pregnancy Outcome Difference between Fresh and Frozen Embryos in Women without Polycystic Ovary Syndrome: a Systematic Review and Meta-Analysis

Xuli Jin et al. Reprod Sci. 2021 May.

Abstract

The purpose of this study is to identify that the advantages of frozen embryos are not evident in ovulatory women or women with non-polycystic ovary syndrome (non-PCOS) by meta-analysis. An exhaustive literature search of PubMed (MEDLINE), Embase, and Cochrane Library databases was performed until March 20, 2020 (limited to articles published in English). We included randomized clinical trials comparing the results of frozen and fresh embryo transfers. The primary outcomes were live birth rate and birth weight. The fixed effect model was used when a significant heterogeneity was observed. Otherwise, a random effect model was used. In 511 identified studies, 4 were eligible and were included in this review. There was no difference in live birth rate, singleton birth weight, clinical pregnancy, ongoing pregnancy, gestational diabetes, and gestational hypertension between frozen and fresh embryos. In frozen embryos, the relative risk of moderate or severe ovarian hyperstimulation syndrome (OHSS) was lower, the incidence rate of pre-eclampsia higher, and the standardized mean difference of twin birth weight higher than in fresh embryos. There is no significant difference between frozen embryo transfer (FET) and fresh embryo transfer in ovulatory women or women with non-PCOS. We recommend that the transfer depends on the actual situation in the patient in clinical practice, rather than the "freeze all" policy and thawing FET.

Keywords: Birth weight; Fresh embryos; Frozen embryos; Live birth rate.

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References

    1. Steptoe PC, Edwards RG. Birth after the reimplantation of a human embryo. Lancet. 1978;2(8085):366. - DOI
    1. Maheshwari A, Pandey S, Amalraj Raja E, Shetty A, Hamilton M, Bhattacharya S. Is frozen embryo transfer better for mothers and babies? Can cumulative meta-analysis provide a definitive answer? Hum Reprod Update. 2018;24(1):35–58. https://doi.org/10.1093/humupd/dmx031 . - DOI - PubMed
    1. Roque M, Lattes K, Serra S, Solà I, Geber S, Carreras R, et al. Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: a systematic review and meta-analysis. Fertil Steril. 2013;99(1):156–62. https://doi.org/10.1016/j.fertnstert.2012.09.003 . - DOI - PubMed
    1. Tang T, Glanville J, Hayden CJ, White D, Barth JH, Balen AH. Combined lifestyle modification and metformin in obese patients with polycystic ovary syndrome. A randomized, placebo-controlled, double-blind multicentre study. Hum Reprod. 2006;21(1):80–9. https://doi.org/10.1093/humrep/dei311 . - DOI - PubMed
    1. Delvigne A, Rozenberg S. Epidemiology and prevention of ovarian hyperstimulation syndrome (OHSS): a review. Hum Reprod Update. 2002;8(6):559–77. https://doi.org/10.1093/humupd/8.6.559 . - DOI - PubMed

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