Egg Quality: new insights into why human eggs don’t age well

It has long been accepted that the primary reason that human eggs don’t age well is due to a dysfunction in when and how the chromosomes separate. This reduced chance of becoming pregnant associated with aging as well as the increased miscarriage rates. A new paper has now demonstrated that it’s not just the DNA separation that declines with time but also how the chromosomes are actually sorted and divided.

Within each egg are cable-like structures called microtubules. These microtubules not only help the egg maintain its shape but also are integral in sorting/separating the DNA. They are also in charge of cell division after fertilization is complete. In fact, some of the most powerful cancer fighting drugs are used to deliberately damage microtubules in order to prevent cancers from growing. This new information provides us with further insight into another important aspect of egg quality.

Although we don’t currently have any specific recommendations on what we can do to improve microtubule function; this information does provide us with more diagnostic information for patients that are going through In Vitro Fertilization (IVF). IVF is not only the treatment that provides patients with the highest pregnancy rates but when performed in a high quality setting; it also provides important diagnostic information. There is no accurate test for egg quality except to put a healthy sperm inside and see if/how well the process of fertilization and development takes place. We routinely use this information in discussing treatment options for patients that do not successfully conceive in their first IVF cycle at our center.

Fertile thoughts,

~Robert

Robert Greene, MD, FACOG

Conceptions Reproductive Associates

How Many EGGS do you think you have left?

You were born with every egg that you’ll ever have. Although studies suggest that there may be a process where we can create eggs; such technology is far into the future. More importantly, you’re losing eggs at a rate that far exceeds what you would guess. Current research suggests that most women will lose about 500 to 1000 eggs per month through a process of attrition called apoptosis—yet only one or two eggs each month will be capable of fertilization. A recent summary of all of the available research has shown that most women will only have about 3% of their eggs remaining by age 40.

Ovarian Reserve Curve from Conception to Menopause.png

Estimated number of remaining follicles (from birth)

Although the slope of that curve appears intimidating, the goal of this blog post is to increase your awareness and to empower you to take action. Some women are born with more eggs than others. Some women will lose their eggs at a faster rate. Most importantly, the eggs that remain in your ovaries at any given moment represent your ovarian reserve. Therefore, it is very relevant for you to consider how many eggs you have now and then plan how many (more) children you think you might someday wish to have.

This diagram shows the various stages of egg development summarized in a single ovary.

Ovary demonstrating egg development.png

It takes an egg several months to develop from its status as a primordial follicle to that of a mature fertilizable oocyte. It is only when they reach that stage that the ovary releases the egg through a process called ovulation. Fewer than 300 of your eggs are likely to ever complete this journey. In other posts on this blog, we focus on various steps you can take to optimize the health of your developing eggs; but for now let’s focus on the future of your fertility in the months and years to come.

At least 99% of your remaining eggs are dormant—alive but not metabolically active. They have been in this resting state since you were a newborn. The eggs that are in these intermediate stages of development—which represents your fertility—can be estimated by a simple well timed blood test. Consider having your ovarian reserve tested today. Then think about how many children you envision yourself having. Consider when you will be ready to start or expand your family. By doing so, you can better estimate whether or not egg freezing or embryo banking (creating and storing embryos for future use) are steps you should be considering to assist you in creating your future family.

EGG FREEZING 2.0; interpretation of emerging data can be confusing

Within days of writing about the modern benefits of egg freezing a new study was published in JAMA based upon old data. They looked at national data from 2013 and concluded that pregnancy rates from egg donors were lower if the eggs had been frozen than if they were fresh. That was probably true back then. But technology is advancing at an exponential rate. Reproductive medicine is arguably one of the most technology dependent fields of medicine. So applying 2013 results to current decision making is flawed from the very onset. Having said that, let’s consider what this publication may be able to teach us and how we should more accurately interpret it today.

This study looked at the 2013 Annual Report of the pregnancy rates from fertility centers in the USA which were collected by the Society for Assisted Reproductive Technology. The science and experience of most centers using this technology has advanced considerably since then.  In fact, it was in late 2013 that the Practice Committee for the American Society for Reproductive Medicine published the guidelines for oocyte cryopreservation.  In their review they pointed out the fact that much of the data that they analyzed was from Europe as few clinics in the USA had published their experience with egg freezing at that time. They also clarified how the difference in techniques used to freeze/thaw the eggs had progressed rapidly resulting in dramatic improvements in success rates. As a result, the removed the “experimental label” from the procedure because of these advances. However one of their most important ultimate conclusions was that “success rates may not be generalizable, and clinic-specific success rates should be used to counsel patients whenever possible.” Despite that clearly stated recommendation, this latest research paper lumped together all of the clinic data and created the latest public misinformation campaign.

Today, many more centers have experience in freezing/thawing eggs using the most modern technique of vitrification. As a result, more patients that need donor eggs are able to benefit from the lower cost and greater convenience of frozen eggs and still enjoy the very best in success rates. Better still, many egg banks offer special guarantees so that if a specific donor’s eggs do not perform well: they will have access to replacement eggs without additional cost. So the best message for patients in need of donor eggs today is to be a wise consumer. Patients should ask their clinical very candidly about their unique experience with frozen donor eggs. I think that they will find greater reassurance in today’s science than in yesterday’s news.