Don’t Give Up On “Poor Quality” Eggs
With decades of experience performing IVF, CHR has become one of the best laboratories for understanding what makes a good embryo. Watch Dr. Gleicher explain our approach to egg selection and what egg quality means during IVF.Want to Consult Dr. Gleicher?
Hi, I’m Dr. Gleicher, the medical director and chief scientist here at CHR. A frequently asked question is, “What is egg quality?” and, “Why is egg quality of such big importance?” Well, the egg is the source of everything. That’s probably the simplest answer.
It is important to understand that even though we all wouldn’t be here if there wasn’t a 50/50 more or less contribution of the mother through the egg and of the father through the sperm in terms of genetic inheritance. But, that 50-50 distribution does not apply to much else. And what I mean by that is that when you think about it, once fertilization happens, the sperm basically enters the world of the egg and therefore, the egg has almost complete control over the quality of the resulting embryo.
Indeed, we believe that roughly 95 percent of embryo quality is determined by the egg and only about 5 percent by the sperm. Now, we may find out that the ratio needs a little bit of adjusting, but there can be no question that because the egg hosts the development of the embryo (because the sperm enters the microenvironment of the egg rather than vice-versa), the egg is much, much more important than the sperm in predicting embryo quality. And embryo quality obviously predicts pregnancy chances with IVF and therefore, the egg is very very crucially, indeed, important in determining pregnancy chances.
Yet, we in IVF over 40 years almost look primarily at the embryo– the end product of that long process of getting the best possible egg, fertilizing that best possible egg, of observing how that initially fertilized egg goes through its first division and then continues to divide. Yet, we look at the end product almost exclusively before making a decision which embryo to transfer. At the same time, it is really the egg where everything starts that has this huge importance for the ultimate embryo quality.
And this discrepancy between what we do and what makes physiological sense attracted us here at CHR for quite some time. And we, therefore, here at CHR a number of years ago, started very carefully looking, not only like everybody else does at embryo quality, but also at egg quality right after retrieval. And when we did that, we published a few papers on the subject since. When we did that, we made some very interesting discoveries.
And probably the most interesting discovery was that there are obviously different outcome combinations. You can have great looking eggs which end up with rather poorly looking embryos. You can have pretty poor looking eggs which nevertheless produce really wonderful looking embryos for transfer. And what we learned is that particularly in the latter case, we sometimes get fooled.
We see those beautiful embryos and make our choices about transfer, and when we don’t get pregnancies in our weekly conference (where we always review all the cycles that have not been successful in leading to pregnancy), we suddenly started seeing that in many of those cycles where we thought that we had transferred absolutely gorgeous embryos, the eggs didn’t look so well. And so that initiated a whole series of investigations which we are still in the midst of, but which already have allowed us to determine certain egg qualities which are warning signals and which we now here at CHR, very carefully consider even if we have at the end great looking embryos.
And, therefore, the point that we are trying to make here with this video today is that there is no question that embryo assessment before transfer and deciding which embryos likely have the best implantation and pregnancy chances is very, very, very important. But, by looking at the eggs from which those embryos were produced, you can glean additional knowledge that allows for additional differentiation of which embryos have really the best implantation chances. And that has, here at CHR, now become the routine. Thank you very much.