Elective Egg Freezing: Borrowed Time - The science of elective egg freezing

In the sixties, the feminist movement told women they could have it all. Women took up the call for equality, fought for rights in the workforce, demanded equal pay, affirmative action—and are still doing so. In many respects, women have proven they can change almost all aspects of their lives. Unfortunately, our reproductive systems never got the memo, and fertility remains one place where women cannot exert their will to change the less-than-ideal window they’re given to conceive children—assuming it’s an option at all. However, a new process called vitrification offers some women the power to pause what may feel like an ever-ticking biological clock. That is, if they have the information, resources, money, timing and reproductive luck required.

Women’s Reproduction

Unlike men, who continue to produce new sperm throughout their reproductive lives, women are born with all the egg cells they will ever have—about two million. As a woman ages, her eggs age too, and their number and quality decline. On average, about 11,000 egg cells die each month from the time a girl is born until she reaches puberty, at which point she will have approximately 300,000 to 400,000 egg cells remaining. Each month after that, another 1,000 egg cells will die until a woman has about 1,000 remaining and goes into menopause. By age 37, the average woman will have about 25,000 remaining egg cells. Over a woman’s lifetime, she will ovulate approximately 45 eggs.

Women’s fertility begins to decline in their late twenties and drops off significantly in their mid-thirties. By age 40, her chance of getting pregnant naturally (without artificial reproductive technology) each month is about five percent. In addition, the risks of miscarriage and complications in pregnancy and childbirth increase. By age 44, her risk of miscarriage is 54 percent. The risk for birth defects and genetic abnormalities also increases as a woman ages: a 30-year-old woman has a 1 in 384 risk of having a baby with a chromosomal abnormality; the risk jumps to 1 in 66 for women aged 40. The risk to expectant mothers also increases—gestational diabetes, high blood pressure and complications from birth make pregnancy a more complicated proposition for women in their 40s.

Yet, when a woman is in her healthiest childbearing years (early to mid-twenties) a family may not fit into her plans even if she knows she wants children. There are a variety of reasons for women to delay a family, such as completing an education, building a career, waiting until they enter the right relationship for raising a family and, of course, economics. Statistics support that, indeed, in spite of social, economic and biological pressures, more women are choosing to delay parenthood. In Canada, the average age of first-time moms has increased from 23 in 1971 to 28 in 2011. And by 2011, one in three women became first-time moms at the age of 35 or older. In fact, for the first time ever, Canadian women aged 40 and older have surpassed teenagers in giving birth.

Delaying pregnancy can mean the end to the possibility of carrying a child. However, a process developed in Canada called vitrification has given women more reproductive options.

Freezing Time

Women have long had access to in vitro fertilization (IVF), the process of harvesting their eggs, getting them fertilized with sperm and freezing the resulting healthy embryos. However, until recently, freezing unfertilized eggs has proven a more challenging process than that of in vitro. One of the reasons why is that although eggs are the largest cell in a woman’s body, they are extremely delicate—more so than embryos. Until 2012, scientists were unable to freeze eggs successfully on a consistent basis without ice crystals forming on the cell membrane. Those ice crystals damage the cell, destroying its viability. Today, a new freezing process called vitrification has improved artificial reproductive technology.

While traditional freezing does not have a high success rate, vitrification does. Cryoprotectant solutions transform the water in the cell into a glass-like solid that does not crystallize when frozen. The cells are then put into a storage straw and plunged into liquid nitrogen, which cools them to -196˚C within two to three seconds. When vitrification is done correctly, 90 percent of egg cells survive the thawing process.

Vitrification has given women the potential to preserve their fertility even as they age. Medical egg freezing can be a viable option for women with medical conditions such as cancer or early menopause who may become prematurely infertile. However, elective egg freezing is generally done by women who are choosing to delay having children and hope that the procedure will increase their chance of becoming parents later in life.

A team of researchers at the University of North Carolina at Chapel Hill have concluded that the ideal time for women to freeze their eggs is when they are 32 or 33. After age 35, it is likely to be less successful, and before age 30 the eggs may no longer be viable by the time a woman decides to conceive. Many clinics will not undertake the process for women over 37 and say eggs must be implanted before age 50 or the chances of a successful pregnancy are too low. Conversely, women who freeze their eggs in their early 30s and later decide to use those eggs have a 40 to 50 percent chance of a healthy pregnancy.

Breaking Down the Process

Whether retrieving eggs for in vitro fertilization or for elective egg freezing, the process is difficult for a woman. She must first inject high levels of hormones into her belly for about 10 days. This increases ovulation and forces her ovaries to produce multiple eggs rather than the typical single egg that she’d normally produce each month. Ultrasound and blood tests tell her doctor when the follicles that produce the eggs are mature and she is given another dose of hormones.

Thirty-six hours later, the doctor retrieves the eggs from her ovaries with a long needle. According to Dr. Tarek Motan, Associate Professor in the Division of Reproductive Endocrinology and Infertility at the University of Alberta, retrieving eggs is a very painful procedure.

He says: “the only thing that justifies all the nastiness I do to nice people, is that childbirth is worse … I control the pain with extremely high doses of medication—I call it manageable discomfort.”

Eggs that are immediately fertilized are placed in a lab dish with sperm. Within three days, healthy embryos can safely be frozen, either with traditional methods or with vitrification. Unfertilized eggs that are being frozen are taken to the lab to undergo the vitrification process.

When a woman is ready to use her eggs, she is given more hormones to prepare her body for pregnancy. The eggs are then thawed and fertilized, but that’s not a simple process. When eggs are frozen and thawed, the outer shell hardens, making it difficult for sperm to do their job.  Technicians, therefore, select the best sperm they can and inject them into the egg cells. Once the eggs are fertilized, technicians pick the healthiest embryo and use a thin tube inserted in the woman’s uterus to transfer the embryo. Once a woman becomes pregnant, she stays on hormones for eight weeks to mimic a natural pregnancy and give the placenta time to take over.

Advancing Science

Vitrification has dramatically increased the survival rate of embryos that women freeze for in vitro fertilization. Previously, 70 percent of embryos survived the thawing process. With vitrification, that number has jumped to 90 percent. This has implications beyond embryo survival rates. Previously, multiple embryos would be implanted to improve the odds of a viable pregnancy. However, that increases the risk of a multiple pregnancy and the attendant dangers to both mother and children—Nadya Suleman, better known as Octomom, is an extreme example.
Vitrification allows doctors to implant one embryo and improve the chances of a healthy pregnancy.

Vitrification has also made accessing an egg donor less difficult for people facing infertility. In Canada, the 2004 Assisted Human Reproduction Act made it illegal to pay a woman for her eggs. However, women and men have access to donated eggs anywhere in the country and can even buy them from clinics around the world thanks to special shipping methods. This access may not only increase a person’s chance of finding an egg donor but also the chance of that donor being of his or her ethnicity—an option that was previously difficult or impossible for many minority couples.

The Debate

Like many reproductive services, egg freezing is not regulated in Canada. However, Dr. Motan says that it is almost impossible to regulate this type of industry:

“You cannot regulate professionalism and good value. Laws try to generalize across people … but my only interest is the best care for my patients.”

Vanessa Gruben, Associate Professor, Faculty of Law at the University of Ottawa, has concerns about the advertising used to promote social egg freezing. In her article “Freezing as Freedom? A Regulatory Approach to Elective Egg Freezing and Women’s Reproductive Autonomy” published in 2017 in the Alberta Law Review, Gruben argues that social pressure and private clinic advertising can influence women’s decisions. One of Gruben’s concerns is that the portrayal of egg freezing as an insurance policy is misleading: “The promotion of elective egg freezing focuses on two main messages: it offers reproductive control and is a form of reproductive insurance.”

The crux of Gruben’s argument is that many women who choose to freeze their eggs are in their late 30s or early 40s and their chances of a successful pregnancy are slim. When they choose egg freezing as an insurance policy, it is an expensive policy that may not pay out. Regardless of advertising, “egg freezing is [not] a guarantee for a future baby.” Dr. Motan’s clinic at the Lois Hole Hospital rarely offers elective egg freezing to older women because “less than 10 percent of eggs are genetically normal by age 40 … Statistically, her chance of getting pregnant is about 0.7 percent. These women are better off accessing donor eggs”—the risk of miscarriage and health of the eggs is related to the age of the donor.

Gruben’s argument is that the clinics that market reproductive services should have to be more transparent about the likelihood of a healthy pregnancy, the physical challenges of IVF treatments and the cost of their “insurance policy.” Dr. Motan thinks about the ethics of his job often. He says his role is to “provide information and then respect my patient’s wishes. I always try to do the right thing and help people.” Since all of the hormones that are used for egg freezing naturally occur in a woman’s body, he sees his work as “manipulating normal processes—it’s not really that artificial.”

While Dr. Motan carefully considers the ethics of artificially assisted reproductive technologies, he also thinks about the

“moms in waiting who have all the skills and instincts—the only thing that’s missing is a little one … We build families, and there is no greater joy than sharing in others’ families.”

The Risks

According to Dr. Motan, there are no known long-term risks of high dose hormone treatment: “We use hormones that naturally occur in the body” at lower levels and for a shorter period of time than during a pregnancy.

Doctors have found no increase in the risk of fetal abnormalities in births from frozen eggs. It is not yet known if there will be any long-term health effects because the first baby born from frozen eggs only turned 30 in 2016.

That said, Dr. Motan advises his patients that their “best chance [of a healthy pregnancy] is to have your baby naturally—do it sooner rather than later. The best technology is always your second choice. Your third choice is to do nothing until you want to be a parent and then you run the risk of needing donor eggs.”

Finances

As with many reproductive technologies, elective egg freezing is expensive and rarely covered by provincial or private insurance. In the Edmonton region, women have access to Alberta Health Service facilities such as the Lois Hole Hospital for Women. There are also private clinics that provide a range of artificial reproductive technology services. Costs of IVF treatment for public and private clinics run from $5,800 (with an additional cost of $600 for egg freezing) up to $15,000. Other costs include hormone treatments and egg storage. It may take several IVF cycles to harvest enough eggs to ensure a healthy pregnancy. Women in their early 30s, who are at the prime age for the procedure, may not have the financial resources to pay for it.

Yet, as women continue to move beyond traditional boundaries, they are accessing reproductive technologies such as vitrification more frequently. And, while science hasn’t given women the ability to ignore biology, that seemingly unrelenting reproductive window is expanding for women with the resources to access technological advances.t8n

The Lingo

Oocyte Cryopreservation: Oocytes (egg cells) are extracted from a
woman’s body, frozen and stored in liquid nitrogen.

Cryoprotectant: A solution that prevents tissue from freezing—often found in nature in frogs and polar animals.

Vitrification: The process that transforms water in a cell into a substance that does not crystallize when frozen.

How to Begin

If you have concerns about fertility, experts suggest beginning with your family doctor or gynecologist for counselling. Your “expectation should not be to get scientific detail, but to begin a discussion and request a referral. Don’t wait for that discussion.” It can take anywhere from three to nine months to get into a public clinic in the Edmonton region.