Incubators & Why They Really Matter

Birdseye View

Embryos are grown in incubators and you should pay attention to the incubators your laboratory uses for two reasons: they may impact the quality of your embryos or the risk your embryos get confused for another patient’s.

Low Oxygen Incubators Are Better

The amount of oxygen in the air we breath is around 20%, but within our bodies, and where embryos thrive, that number is 5% or even lower. Today, 30% of laboratories still use higher oxygen pressure in their incubators and according to one nice, prospective study from Frisco Institute of Reproductive Medicine, that probably drives worse outcomes. Ask if your clinic’s laboratory uses oxygen pressure of 5% or lower.

Uncrowded Incubators Are Better

You should prefer your embryos will be in an incubator with few, if any, other patient’s samples. This is for two reasons.

Better Culture Conditions


Embryos need to be continually checked and fed. Most incubators are “big box” and look like a dormitory mini-fridge. When other samples in a “big box” incubator need checking, the door is opened, the elements sweep in and all samples are subject to lower temperatures and higher oxygen pressure. Conversely, “desktop” incubators give each sample it’s own chamber. Samples are not perturbed when others are checked and thus incubator conditions are more stable. As one clinic in Japan recorded, this had an impact on the percentage of their embryos that properly matured.

Ask your clinic if your sample can be kept in a “desktop” incubator. “Big box” incubators are commonplace and if your embryos will be in one, in an ideal world, they would have their own incubator or be placed in an incubator with very few other samples.

Risk of A Mix-Up


If your sample is in a “desktop” incubator, your sample has it’s own chamber, and is less likely to be confused with another patient. If your sample is in a “big box” incubator, the risk of a mix-up probably rises (though we don’t believe this has been studied). Ensure your clinic has procedures in place to mitigate the risk by labeling (or bar coding) all sample dishes and ensuring two people witness and sign-off on any actions taken with your embryos.

Time Lapse Imaging Systems -- Do They Help?

Laboratories are beginning to adopt Time Lapse Imaging systems. These are camera and software systems designed to chart an embryo’s growth within the incubator all the while causing minimal disturbance to the embryo. Time Lapse can be used just for embryo selection or as part of a larger system (sold with a specialized incubator). To date, few of the well-run studies show it confers a benefit. Below is a rundown of the five studies that compare Time Lapse versus conventional processes. In four of the five studies, Time Lapse showed no statistically-significant improvement.


If your clinic has a satisfactory 40 - 60% rate of growing Day 5 blastocysts, we do not think Time Lapse is helpful. If your clinic cannot grow Day 5 blastocysts, and therefore must guess which Day 3 embryos will be best, it could be a useful tool.

Pro Tips

  • Ensure your laboratory uses 5% or lower oxygen levels in its incubators

  • Request your cells be kept either in a desktop incubator or in an incubator with as few other samples as possible

  • Ask what steps your laboratory has in place to avoid mixing up your embryos with other patients’ embryos
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