Low oxygen environment facilitates embryo availability for older ovarian responders (PORs)

Abstract

We aimed to investigate the different effects of low oxygen (5% O₂) and atmospheric oxygen (20% O₂) on in vitro fertilization for older poor ovarian responders (PORs). We selected 1080 older PORs who met two criteria: (i) advanced maternal age (≥40) and (ii) an abnormal ovarian reserve test. All the patients used the ultra-short term protocols with GnRH agonist and recombinant FSH for controlled ovarian hyperstimulation (COH). About 506 cycles were performed in the incubators with 5% O₂ and 574 cycles were performed in the incubators with 20% O₂. No significant differences were observed in normal fertilization rates (59.68 versus 60.25%; p = .691) and cancelation rates (18.97 versus 19.34%; p = .879) between two groups. The number of available embryos (1.77 ± 0.57 versus 1.52 ± 0.50; p = .041) and mean number of cells on Day 3 (7.49 ± 1.82 versus 7.16 ± 1.70; p = .032) were significantly higher in 5% O₂ group compared to that in 20% O₂ group. It showed no significant differences in the implantation rates (27.43 versus 24.11%; p = .803) and clinical pregnancy rates (36.34 versus 30.05%; p = .307) between two groups. The employ of low oxygen culture did not improve clinical pregnancy rate for older PORs. However, it benefited early embryonic development for older PORs.

Chinese abstract

我们旨在研究辅助生育中, 低氧（5% O²）和大气氧（20% O²）对年长卵巢反应不良（PORS）女性的体外受精的胚胎发育的不同影响。我们选择了1080位年长女性, 她们需符合以下两个条件：（i）高龄孕妇（≥40）和（ii）卵巢储备功能异常。所有患者使用GnRH激动剂和重组FSH的超短期方案, 用于控制性超排卵（COH）。506个周期在5% O²的培养箱中进行, 574个周期胚胎在20% O²的培养箱中进行。两组间受精率（59.68%／60.25%；P＝.691）和周期取消率（18.97%／19.34%；P＝.879）无显著差异。与对照组相比, 5% O²组的有效胚胎数（1.77±0.57±1.52±0.50, P＝.041）和3天胚泡的平均细胞数（7.49±1.82和7.16±1.70；P＝.032）显著高于对照组。两组植入率（27.43%／24.11%, P＝.803）和临床妊娠率（36.34%／30.05%, P＝.307）无显著性差异。辅助生育中, 低氧培养虽不能改善高龄女性的临床妊娠率, 但是有利于她们的胚胎的早期发育。

Keywords:

• Low oxygen
• PORs
• embryonic development
• clinical outcomes

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was supported by Shaanxi Technology Committee Industrial Public Relation Project [Project Number: 2017SF-284].