A Cold Look at Egg Banking

Cryopreservation of Oocytes

Nothing ordinary here.

Egg banking is unlike other kinds of investments because it serves an uncertain need for an unpredictable time.

It isn’t like a stake in a lottery or casino, apart from elements of luck and judgment. A woman won’t know the outcome of her gamble for years, and then she may no longer care about winning.

Although sometimes called insurance, there’s no assurance of benefit.

Unlike paying for a piece of merchandise, the purchaser buys access to a product from her own body.

When required to counter premature sterility, we call it fertility preservation. But most women have no urgent need to bank their eggs, apart from worrying about the inevitability of natural aging. They seek to safeguard future fertility “just in case.”

A healthy young woman who asked if egg banking is “right for her” looked surprised when I hedged a reply with “perhaps” and “maybe.” To paraphrase her: “I don’t want to interrupt my career at this stage to begin a family and haven’t found the right partner yet. But I worry if fertility lets me down when I am ready for motherhood. I dread the risk of being childless the rest of my life or forced to choose another parenting option. I thought you’d be more enthusiastic about freezing since you did research.”

I had sown doubts in the woman’s mind without meaning to dash her confidence in the endorsements she read in celebrity magazines or on Instagram and TikTok. Women ranging from early 20s to almost 40 claimed egg banking had helped them feel “empowered,” confident in their “perfectly frozen eggs,” and relieved from anxiety about their “fertility journey.”

I don’t count myself as an expert after retiring from research. I still hold professional views, although they don’t always mirror my gut feelings. That’s being human. I doubt I would deny help to a daughter wanting to bank eggs, even if I preferred to ease her mortgage by the same amount instead. We are talking about imponderables—whether she will need to retrieve eggs from a freezer and if they can make babies.

We constantly confront probabilities in life (chance occurrences) which is not to say the same as possibilities (something that can happen at all). Two rational people can reach opposite conclusions from the same facts from different experiences or values. Take, for example, my cocky assurance at age 20 that I wasn’t at risk of a serious motorcycle accident, whereas my mother dreaded it, having worked in an orthopedic ward.

There’s no shortage of advice online about “elective” egg banking (also called “social”). Kristen Brown offers sensible advice about fertility topics on her podcasts, but I am stretched to offer any original or helpful thoughts. And so, I begin with a primer for readers unfamiliar with cryopreservation or curious about how it emerged. Others can cut to the chase and skip the next section.

A Killing Frost

Some plants have tolerated our night frosts while others succumbed to the wintry scene outside. Few animals have cells that can survive freezing temperatures and thawing, but none of them warm-blooded creatures to my knowledge, including humans. The chief agents of mortality are ice crystals and concentrated salt.

In my Cryobiology 101 class at Edinburgh, I used to compare the effects of freezing tubes of diluted blood after treating half of them with glycerol and spinning in a centrifuge. Hemolysis turned the solution red in the control tube, whereas a red pellet at the bottom of the other tube showed glycerol had protected the cells.

A long trail to the discovery of glycerol as an effective cryoprotectant ended by accident in a London lab in 1949. Major benefits flowed straight away. Cryopreservation revolutionized cattle breeding when frozen semen could be shipped from superior breeds to farms worldwide. That’s why we pay so little for a gallon of milk. The first human sperm bank opened in America to preserve fertility potential for men preparing for sterilizing cancer treatment or vasectomy.

However, glycerol permeates egg membranes slowly, making it a poor cryoprotectant. When a new Italian law prohibited embryo freezing (long since rescinded), clinics had a greater incentive to store eggs. An alternative cryoprotectant improved results, but most centers remained cautious. Evidence accumulated that slow cooling causes the spindle apparatus to weaken, putting at risk the fidelity of chromosome separation at conception. I tried to optimize egg freezing with the leading British cryobiologist, the late David Pegg, whose primary goal was freezing kidneys for transplantation (that came closer last year by “nanowarming” vitrified rat kidneys). We were on the wrong track and should have adopted vitrification to avoid freezing injury.

The vitrification method involves immersing cells in a very viscous medium before plunging them in liquid nitrogen. Ultra-rapid cooling avoids spindle damage and stops water molecules from aligning in orderly arrays to create ice crystals. In the chaos, the medium turns into a glassy semi-solid instead of freezing, comparable to the difference between amorphous candy (candyfloss) and crystalline table sugar.

The Japanese biologist Masashige Kuwayama perfected vitrification, already proven to work in other labs. Elegant in its simplicity, his method dexterously handles individual cells with a simple device called a Cryotop. He got outstanding survival rates with cattle eggs and they soon translated to humans—and here we are! Vitrification of eggs and embryos is routine in clinics all over the globe and may even replace a freezing method I developed for solid ovarian tissue (see a future Substack).

Life Suspended in Glass

I imagine thousands of women privately agonize over the decision to store eggs. They ponder the cost; they wonder about the process; they waver between clinics; they might later have a buyer’s regret.

Private anxieties can be compounded by emotional pressures. Hopeful grandparents hovering in the background; friends trying to sway a decision. Fees for the service cast the longest shadow. Compared to electronic goods that become more affordable over time, medical costs rarely taper off from the economies of scale.

Some prestigious tech firms subsidize fertility treatment as a perk for employees and in the self-interest of retaining skills in the company. Critics snap that it traps employees by making them feel indebted. They urge employers and governments to address underlying issues of work-life balance and workplace equality instead of normalizing delayed motherhood, which isn’t optimal for reproductive health even with eggs still “young” from languishing in the cold. Accommodation of more flexible work schedules, funding parental leave, and childcare would enable women to start a family at liberty and probably earlier, like past generations.

However, few young and single women have a corporate patron or a family benefactor. Little remains from their modest income after paying for the necessities of life plus a set-aside to replace a rusty clunker in the driveway.

I used to reckon from national statistics that on average only four eggs in every 100 harvested produce IVF babies. Assisted reproduction is inefficient. Harvesting the rarest cells in the body comes at a premium price of the order $1,000 each. [That should put American gripes about the rising costs of grocery store eggs in perspective!]

The data have improved, but about 20 eggs are needed for a fair chance of an ongoing pregnancy either with or without prior banking. Hence, two cycles of egg collection are needed, or even more at late reproductive ages. On top of this outlay, there are annual costs of banking and, further off, IVF and embryo transfer. Although we plan from averages, the spectrum of results is broad between repeated disappointment and speedy triumph. All we dare say with confidence is the more eggs available the better, but that is more discouraging than helpful.

Most women who delay motherhood with banked eggs will get pregnant naturally with no need for them. Likewise, few men use cryopreserved semen, although circumstances are so different between the sexes that it’s an imperfect parallel. We don’t agonize over the disposal of redundant sperm because they are wasted naturally all the time. Disposal of spare eggs is another matter. They were obtained at far greater trouble and expense, with discomfort and even risk for women with polycystic ovaries. I wonder if some redundant eggs will eventually be donated so others can benefit who didn’t bank their own and lost the bet.

There is a compelling humanitarian case for banking eggs (or ovarian tissue) when childless women are imminently at risk of sterilization. Some welfare states cover their fees for fertility preservation, but Medicaid in the U.S.A. doesn’t help those patients in financial hardship, except for five states. Senator Cory Booker introduced legislation in 2023 that, if enacted, will require more insurance plans to cover those costs in a bundle with cancer treatment. Too many patients appeal for public charity as a last report.

If I had a daughter electing for the service, I hope she would be as discerning and diligent as any other major investment, like a home or stocks and shares. I would urge her not to rush into a decision without thoroughly reviewing procedures, medical providers, and laboratory security. She should budget for at least two cycles of ovarian stimulation and the other often overlooked costs. The emotional toll of making hard decisions also needs weighing, including the possibility of donor sperm if she stays single. Finally, it’s a wise precaution to leave a record and name of her clinic in a will.

When I reviewed this text, I noticed the word need came up multiple times. It’s a shifty word. Besides the kinds of needs we all agree on, there are personal “needs” that carry more weight with some people. If I have sounded rather discouraging in this essay it is only to urge caution. For what does my expertise count when I have no direct experience of a family member or friend facing this knotty issue? For most of us, the bringing of new life into the world is our most consequential act, and safeguarding that decision is an intensely personal matter. Egg banking is the right decision for the right person, and no one knows better than the individual herself.

Image: Laboratory fog after opening a liquid nitrogen tank (generative AI)

Next post: Fertility Treatment versus the Population Bomb