5 Common Questions about the Egg Freezing Process
It is a known fact that people with ovaries are born with a finite number of oocytes (also known as eggs). The ovary is, unlike a testicle, a non-regenerative organ. Due to this phenomenon, there is a constant attrition of eggs over the span of reproductive life (from some 1-2 million at birth, to a quarter million at the beginning of puberty, to several hundred at the time of menopause). However, at any point in time, there are more eggs contained within the ovaries than anyone would ever use. In fact, from the beginning of reproductive life (12 years old is the average age) until menopause (51, on average), a person would only ovulate approximately 450-500 eggs, barring an individual never uses hormonal birth control, gets pregnant, or breastfeeds.
So why do we need all these eggs? Why would a newborn have 2 million eggs? And remember that in people with testicles, the attrition is even greater (as they contain millions of sperm cells in each ejaculate). I have spent 15 years of medical education and training, in part, to be able to understand the function of these organs and answer the above questions and the likely explanation that I’ve found over years spent researching human reproduction is rather simple- we as species, are not very efficient in our reproductive process, in part, because our reproductive cells (eggs and sperm cells) contain numerous errors. So the survival of the fittest is ensured though the power of numbers.
There is a common misconception that female fertility diminishes with age due to the ever diminishing number of oocytes across our reproductive lifespan. That is actually untrue! We are not more fertile in our twenties than in our forties because our ovaries contain more eggs in our twenties, and we somehow ovulate more eggs when we are younger. Humans are mono-follicular species, which means that most individuals (with a few rare exceptions) ovulate only one egg each menstrual cycle. This is why humans (similar to other mono-follicular species such as sheep or elephants) typically have one baby at a time and not a litter, in contrast to poly-follicular species (for example, cats or mice).
The reason why female fertility declines with age has nothing to do with the declining numbers of eggs, but everything to do with declining quality of eggs.
So what is egg quality?
Egg quality represents an egg’s ability to, when fertilized by a sperm cell, give rise to a chromosomally healthy embryo. That is a sole function of an egg. And as any other cell in our body that does not regenerate (such as heart muscle cells or neurons), its function declines with aging. So for instance, when hair follicular cells age and their function declines as a consequence, they are not producing enough pigment called melanin, and hair grows out discolored or grey. When an egg’s function declines, it is more likely to create a chromosomally unhealthy embryo which most commonly doesn’t implant into the uterus (so we get a negative pregnancy test at the end of the month of trying to conceive), or it implants, but its implantation is inadequate, which results in a pregnancy loss. And these are the exact measures we use in epidemiologic studies that demonstrate decline in female fertility associated with increasing age: 1. there is a lower chance of getting pregnant per month; 2. there is a higher chance of a pregnancy loss per month.
Now that we have learned this, we can turn our attention to the socio-economic changes we, as a society, face on the other side. Even though our bodies (our eggs and ovaries) are at their peak reproductive function in our teens and twenties, our social functioning has drastically changed within the past century.
With the advent of medicine, nutrition, technology and economy, the average life expectancy for women in the US has increased tremendously to 80 years-old. Moreover, we live healthier lives longer, devoid of age-related diseases including diabetes, cardiovascular disease, and cancer. If you have a baby in your forties today, you will most likely be able to spend more time with that child than if you had had a baby at 15 years of age a century or two ago (in the setting of a significantly shorter lifespan back then, due to poor nutrition, wars, infections, sanitary conditions etc). We delay childbearing for various reasons: pursuing education and a career, prolonging our adolescence, lack of a partner, or financial reasons.
Unfortunately, our eggs didn’t get the message. They still decay, leaving us less fertile at the time of our lives at which more and more of us are ready (mentally, physically, socio-economically, financially) to have a child. And the science has, unfortunately, not yet come up with a solution to maintain the good quality of our eggs for a longer proportion of our lives.
This is where fertility preservation comes in to place. It is currently the only way that can help prevent age-related fertility decline. Patients typically have common questions when it comes to egg freezing:
1. When should I freeze my eggs?
By freezing your eggs at a younger age (ideally before the age of 35), you will preserve them in the state of quality (or ability to create a healthy embryo) that corresponds to the age at which you have frozen them, regardless of the age at which you wish to use them.
2. What does the egg freezing process entail?
This process entails controlled ovarian stimulation using recombinant pituitary hormones (called FSH and LH) for usually 7-11 days, in order to stimulate more eggs to mature in that particular cycle (and not only 1, which is what are bodies naturally do). These medications are given in form of subcutaneous injections, similar to how an epi-pen or insulin are administered.
3. Is the egg freezing process painful?
The procedure of egg retrieval is fairly quick (rarely longer than 2 or 3 minutes) and extremely low risk as it is performed using a minimally invasive approach under ultrasound guidance. It is also completely painless, as it is done under sedation- the same kind that would be used for simple procedures like endoscopy, colonoscopy, or wisdom teeth removal. A majority of people will not experience any pain either during the stimulation or after the retrieval, but bloating and pressure are present in roughly 30% of the those who undergo this procedure.
4. What happens when I'm ready to use my frozen eggs?
Should you need to use your eggs in the future, they will have to be fertilized with sperm using a technology called intracytoplasmic injection (ICSI), due to hardening of the outside layer that surrounds the egg called zona pellucida. This technology has successfully been used since 1991 and today represents the most common way of creating embryos in the embryology lab, regardless of whether the eggs have been previously frozen or not.
5. How many eggs should I freeze?
The number of eggs to freeze will depend on the age at which you are pursuing the process, due to their declining quality. I discuss all of these aspects in much more detail with my patients and your reproductive endocrinologist should too.
All in all, I am a huge supporter of fertility preservation especially as many individuals continue to pursue parenthood at older ages. In fact, I envision that in not so distant future, fertility preservation will become part of primary preventative medical care, as its goal is to prevent an age-related condition. This is, at least, the future I sincerely hope for.
Individuals living in Manhattan, Brooklyn or Westchester who are interested in freezing their eggs should consider scheduling an egg freezing consultation with one of the reproductive endocrinologists and in fertility specialists at RMA of New York.