Low versus atmospheric oxygen tension for embryo culture in assisted reproduction: a systematic review and meta-analysis

Although we observed a small improvement in live birth/ongoing pregnancy and clinical PRs, the evidence is of very low quality and the best interpretation is that we are still very uncertain about differences in this comparison.

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Authors

Carolina O. Nastri, Ph.D., Beatrice N. Nóbrega, M.D., Danielle M. Teixeira, M.D., Jowanka Amorim, M.Sc., Lívia M.M. Diniz, M.D., Marina W.P. Barbosa, M.D., Vanessa S.I. Giorgi, M.Sc., Vicky N. Pileggi, M.Sc., Wellington P. Martins, Ph.D.

Abstract

Objective

To appraise the available evidence comparing low oxygen (LowO2) and atmospheric oxygen tension (AtmO2) for embryo culture.

Design

Systematic review and meta-analysis.

Setting

Not applicable.

Patient(s)

Women undergoing assisted reproduction using embryo culture.

Intervention(s)

Embryo culture using LowO2 versus AtmO2.

Main Outcome Measure(s)

Reproductive, laboratory, and pregnancy outcomes.

Result(s)

A total of 21 studies were included in this review. All used O2 concentration between 5% and 6% in the LowO2 group. Considering the studies that randomized women/couples, we observed very low quality evidence that LowO2 is better for live birth/ongoing pregnancy (relative risk [RR] = 1.1, 95% confidence interval [CI] 1.0–1.3) and clinical pregnancy (RR = 1.1, 95% CI 1.0–1.2). Considering the studies that randomized oocytes/embryos, we observed low quality evidence of no difference of fertilization (RR = 1.0, 95% CI 1.0–1.0) and cleavage rate (RR = 1.0, 95% CI 1.0–1.1), and low quality evidence that LowO2 is better for high/top morphology at the cleavage stage (RR = 1.2, 95% CI 1.1–1.3). No studies comparing pregnancy outcomes were identified. Several studies used different incubators in the groups—a new model for the LowO2 group and an old model for the AtmO2 group. The risk of detection bias for the laboratory outcomes was high as embryologists were not blinded.

Conclusion(s)

Although we observed a small improvement (∼5%) in live birth/ongoing pregnancy and clinical pregnancy rates (PRs), the evidence is of very low quality and the best interpretation is that we are still very uncertain about differences in this comparison. The clinical equipoise remains and more large well-conducted randomized controlled trials are needed. They should use the same incubators in both groups and the embryologists should be blinded at least when evaluating laboratory outcomes.

Read the full text at: http://www.fertstert.org/article/S0015-0282(16)300...

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.

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