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April 1, 2013

Oxygen and Embryos

oxygen and embryos

A human embryo naturally develops within the confines of the fallopian tube before its implantation within the uterine cavity.  Since the first IVF cycle in 1977, efforts have been made to refine the lab incubator environment to mimic the natural environment of the fallopian tube.  This includes temperature and nutrients but also importantly the concentration of gases surrounding the developing embryo.

The air we breathe contains approximately 78% nitrogen gas, 22% oxygen and less than 1% carbon dioxide (CO2).  Embryo incubators commonly used 5% CO2 mixed with room air (22% oxygen).  Increasingly, it has been demonstrated that human embryos prefer a lower percent of oxygen.  Oxygen concentration in the fallopian tube is only about 8%; in the uterus, it is as low as 2%.

A recent publication from Denmark (“Effect of oxygen concentration on human embryo development evaluated by time-lapse monitoring”  Fertility Sterility Vol 99, No.3 March 1 2013 pp. 738-44) compared embryos grown in 5% oxygen versus those in 20% oxygen.  Comparisons were able to be monitored by the unique time-lapse monitoring provided by the EmbryoScope.  The Fertility Centers of New England was directly involved in the original development of the EmbryoScope as well as the first IVF births in the United States from this technology.

The authors of this study reported that embryos grown in 20% oxygen were delayed compared to embryos in the 5% oxygen environment.  Specifically, the timing of the third cleavage or division stage was delayed.  Furthermore more embryos successfully reached the day 5 blastocyst stage when cultured in a lower percentage of oxygen.

Switching from 20% to 5% oxygen may sound like a simple matter of turning down the dial.  In reality, it is a timely and expensive endeavor involving complete replacement of embryo incubator systems.  At the Fertility Centers of New England, the lab has been completely converted to a low oxygen embryo environment.  With this and other changes, we have seen quantifiable improvements in embryo development and pregnancy rates.  The Fertility Centers of New England is committed to maintaining a state-of-the art laboratory environment to optimize your patient care.

Have questions about the EmbryoScope and how FCNE can help you? Contact us, today!

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Medical Director,
Fertility Centers of New England