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Fresh versus Frozen Embryos for Infertility in the Polycystic Ovary Syndrome

Zi‐Jiang Chen, Yuhua Shi, Yun Wei Sun, Bo Zhang, Xiaoyan Liang, Yunxia Cao, Jing Fan Yang, Jiayin Liu et al.

New England Journal of Medicine, 2016

1,508 participants · 839 citations

Abstract

BACKGROUND: The transfer of fresh embryos is generally preferred over the transfer of frozen embryos for in vitro fertilization (IVF), but some evidence suggests that frozen-embryo transfer may improve the live-birth rate and lower the rates of the ovarian hyperstimulation syndrome and pregnancy complications in women with the polycystic ovary syndrome. METHODS: In this multicenter trial, we randomly assigned 1508 infertile women with the polycystic ovary syndrome who were undergoing their first IVF cycle to undergo either fresh-embryo transfer or embryo cryopreservation followed by frozen-embryo transfer. After 3 days of embryo development, women underwent the transfer of up to two fresh or frozen embryos. The primary outcome was a live birth after the first embryo transfer. RESULTS: Frozen-embryo transfer resulted in a higher frequency of live birth after the first transfer than did fresh-embryo transfer (49.3% vs. 42.0%), for a rate ratio of 1.17 (95% confidence interval [CI], 1.05 to 1.31; P=0.004). Women who underwent frozen-embryo transfer also had a lower frequency of pregnancy loss (22.0% vs. 32.7%), for a rate ratio of 0.67 (95% CI, 0.54 to 0.83; P<0.001), and of the ovarian hyperstimulation syndrome (1.3% vs. 7.1%), for a rate ratio of 0.19 (95% CI, 0.10 to 0.37; P<0.001), but a higher frequency of preeclampsia (4.4% vs. 1.4%), for a rate ratio of 3.12 (95% CI, 1.26 to 7.73; P=0.009). There were no significant between-group differences in rates of other pregnancy…

How strong is the evidence?

Evidence Hub reads this as a randomized trial. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 1,508 participants or records.

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