"Egg quality" is touted as the single most important aspect of fertility treatments such as egg freezing as IVF. That's because only a quality egg can become a healthy baby. But for egg freezing, there is currently no universal measurement for egg quality. We dive into why this is and what the future holds for egg freezers.
Before elective cryopreservation (social egg freezing) was widely offered as a routine treatment option for women (dropping the label of “experimental” from national organizations and increasing success rates through vitrification freezing techniques were key catalysts), egg freezing was only an option for those who were suffering from medical issues that would eventually take their toll on their fertility (medical egg freezing). The acceptance of social egg freezing by fertility providers has changed the landscape of In-Vitro Fertilization treatment, allowing for women to access a different set of options when it comes to family planning.
By now, many fertility clinics around the world offer social egg freezing, marketed to a woman who wants to plan her future on her terms. Egg freezing is an option for people who want to be proactive about their future fertility potential if they are not ready to start a family. The decision to freeze eggs or embryos (which would require a sperm source to the eggs) depends on the patient's reproductive goals. However, even social egg freezing, with all its technological advancements to date, should not be considered a fertility insurance policy as there are no guarantees in terms of the quantity or quality of eggs frozen. Downstream considerations like sperm quality, as well as a receptive uterine environment for the embryo to implant and thrive are other factors that should be considered.
Everyone has been lectured on the female biological clock; as women get older, the quantity and quality of eggs decreases. The truth is that women reach a “reproductive menopause” (the inability to conceive) about a decade before their true menopause. As a general rule, the younger the patient, the more effective the egg freezing process will be in terms of quality and quantity of eggs.
Why does egg quality matter for egg freezing?
A low quality egg, in simple terms, is one that is chromosomally abnormal. A poor quality or chromosomally abnormal egg is less likely to make it through all the hurdles (fertilization, implantation, full term pregnancy) of getting pregnant and staying pregnant, whether that's through a future round of IVF using your frozen eggs or if you're trying to get pregnant on a given month. Low quality eggs with chromosomal abnormalities are the most common cause of early miscarriage - the older you are, the more likely your eggs are to be low quality, which is why miscarriage rates increase as you age.
Egg quality is important for egg freezing because it is the number one indication that an egg will successfully fertilize, implant and lead to a healthy baby.
But here comes the kicker.. there is currently no method to evaluate the egg’s quality. Fertility doctors have methods to assess the ovarian reserve (bloodwork hormones such as Follicle Stimulation Hormone (FSH) and anti-Mullerian hormone (AMH), and ultrasounds that detect the number of antral follicles), but these are more of an indirect measure of egg quantity.
There is no universally accepted method for determining the quality of eggs before freezing
For unfertilized eggs, there is no scoring system that currently exists, which would allow embryologists to analyze the quality of eggs once they are retrieved from the ovaries. In lieu of this, embryologists follow specific guidelines to determine which eggs are most mature. The logic being that mature eggs are more likely to have gone through all the phases of chromosomal processing in order to be deemed good quality.
"When I had my eggs frozen, I was confused about the difference between 'maturity' and 'quality.' After my retrieval, the embryologist looked at my eggs through a microscope and used specific markers of maturity. I was told that only the ones that had reached a specific maturity level were worth freezing. But, what I didn’t fully grasp at the time was: even if you retrieve the same number of mature eggs, the success rate of those eggs changes based on how old you are. So while it was great to have more 'mature' eggs, I realized that I had to follow the success rates based on my age in lieu of having a certain quality metric."
- Brittany Hawkins, co-author of Everything Egg Freezing
This is not the case in IVF wherein a scoring system exists for embryos, once a sperm has successfully fertilized the egg. In the case of egg freezing, the embryologist, the fertility doctor, and the patient don’t know much about the quality of eggs being frozen.
“There is no good way to test whether the eggs that women have frozen are of good quality (have normal chromosomal makeup). The only way to know if the chromosomes are normal is to fertilize the egg with sperm, create an embryo and then biopsy the embryo and perform preimplantation genetic testing on the embryo. If the embryo has a normal number of chromosomes, then you know that the egg that it came from is also normal.” - Dr. Diana Chavkin, HRC Fertility, Los Angeles
Age is an indication as to how many mature eggs a person would need to get the outcome they want but They may use simple online calculators that only take a woman's age and the number of eggs frozen into consideration, but not the actual eggs themselves. Feedback on the eggs will only come later when eggs are eventually thawed, and the final outcome is revealed. Online calculators are a very generic approach.
What innovations are happening in the field of egg freezing?
1. Fertility benefits through employers
Large companies are starting to offer fertility treatment coverage to employees in their benefit packages and health insurance coverage is recognizing egg freezing as well. New startups have emerged to cater to this challenge. Carrot and Progyny for example, are companies that help employers get set up with fertility health benefit plans. The media attention continues to grow, and people are more educated on this topic and the technology that comes with it.
2. Support resources
After deciding to learn more about egg freezing, patients can use different forms of support. Most support resources have previously focused on the challenges of infertility. For example, RESOLVE is a non-profit organization that advocates for fertility legislature and hosts a series of infertility support groups around the US. When it comes to support resources for egg freezing, ELANZA Wellness has a growing support community that features expert-led events, shared stories from fellow freezers as well as small groups focused on specific egg freezing timelines or reproductive health factors such as PCOS or endometriosis.
3. Egg quality assessment technologies
In terms of insights into a patient's eggs, or their personalized chance of success, Toronto-based startup, Future Fertility, is working to fill this void. They are the first company to produce an oocyte (egg) assessment tool using artificial intelligence (AI) analysis of the images. As more images are added to the AI database, predictions about an egg’s likelihood of becoming an embryo become more accurate. In the future, this means that upon egg retrieval, an embryologist would take a photo of the egg while it is under the microscope. The embryologist would then upload the image to AI egg assessment software to be analyzed. For the first time, patients can take home photos of their eggs, along with an in-depth explanation of what they are freezing (see example below).
Recently, a study was performed comparing their AI-assessment tool, Violet™, to the naked eye of 17 senior embryologists across the globe. Both the embryologists and the AI tool predicted the outcome of 300 eggs. Violet™, was able to predict successful fertilization and blastocyst with 20% more accuracy than the embryologists. This is the first clinical evidence that the quality of an egg can be measured (with the use of AI) and this breakthrough will open doors for patients in terms of transparency (what's actually being frozen) and the clinician’s ability to tailor treatment accordingly.
As with most AI technologies, the accuracy of Violet's™ predictions will get better over time as more data is added into the overall set. So, it is not a perfect science quite yet nor is it offered by all clinics. It does, however, give us an exciting glimpse as to what the future holds for egg quality assessment.
What egg quality measurement cannot tell you
Even with the advent of egg quality measurement technology, it still cannot tell you with 100% accuracy if that egg will become a healthy baby. Because, let's not forget, it takes two to tango! You need both a health egg and a healthy sperm to get through to the finish line. To put this in perspective, 30-40% of infertility cases are due to the male.
Prediction tools can help you understand how many eggs you may need and how many cycles that would take you but only when you get to using the eggs, will you understand exactly how many of those quality eggs are viable using the sperm of your choice.
The net net...
There's an exciting future for egg freezing and technology is rapidly coming to the rescue. At this moment, egg quality assessment still has some time to go but we are nearly there.