IVF culture oxygen levels 'high, limit embryo quality'
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| Picture by Infertility IVF PCOS |
MedWire News: The concentrations of oxygen commonly used to culture embryos in vitro limit blastocyst development, say scientists who recommend an alternative method for increasing yield.
In a normal pregnancy, embryos are exposed to oxygen concentrations of 2-8 percent, but in vitro embryo cultures are typically maintained at atmospheric oxygen levels of 20 percent.
The small amount of available research indicates atmospheric oxygen levels inhibit normal embryo development.
To investigate further, Mustafa Bahceci (Bahceci Women's Health Care Center, Istanbul, Turkey) and co-workers randomly allocated sibling oocytes to culture conditions that mimicked the physiological norm (6 percent carbon dioxide, 5 percent oxygen, and 89 percent nitrogen) for 6 days from insemination, or to atmospheric oxygen levels (20 percent) and the same carbon dioxide and nitrogen levels for 3 days after insemination, before switching to physiologically normal conditions.
Exposing embryos to a physiological-normal gaseous environment improved blastocyst yield at day 6 after insemination from an average of 42.4 to 47.7 and significantly improved overall embryo quality.
Bahceci and colleagues say:
Increased blastocyst yield with better quality may cause improved pregnancy, implantation, and delivery rates in a physiologic oxygen environment.
They conclude modifying the oxygen concentrations used in IVF cultures might improve pregnancy rates after IVF.
© 2008 Current Medicine Group Ltd, a part of Springer Science+Business Media
Source: Fertility and Sterility 2008; Advance online publication
Category: embryo, embryo transfer, IVF
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