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Don’t count on having kids if you freeze your eggs

Michele Harrison froze 21 eggs. Only one was suitable for IVF.

August 14, 2019
Conceptual illustration of a woman holding her pregnant belly that also looks like a clock
Conceptual illustration of a woman holding her pregnant belly that also looks like a clockAmrita Marino

When Michele Harrison turned 40, she decided to sell her New York City apartment to buy a bigger one. She could afford it after laser-focusing on her career, working late nights as a single woman, traveling constantly for ad agencies and then in marketing at ESPN.

While in the process of selling, she temporarily moved in with her aunt in the suburbs. She began to notice how nice it was to see green grass and have room to breathe. She quit her job and swapped her hard-charging big-city existence for the wide-open panoramas of Colorado.

One of the first tasks was a routine checkup with a gynecologist. By this time, Harrison was 41. At her appointment, the doctor got right to the point: “Do you want to have a baby?”

“I was like, ‘I have no idea,’” says Harrison. “I was in shock. I don’t think I ever really thought about having kids or about how old I was, because I had been so focused on my career.”

Her doctor referred her to the Colorado Center for Reproductive Medicine (CCRM), which has a reputation for helping “older” women get pregnant. When it comes to fertility, 35 is the tipping point that medicine calls AMA, or “advanced maternal age.” It’s not an arbitrary designation. A woman’s fertility starts to wane around age 32, and the decline picks up speed by 37, according to the American College of Obstetricians and Gynecologists.

“If you want to freeze your eggs,” she was told, “now is the time.” She joined the growing number of women trying to delay biology. More than 7,000 US women froze their eggs in 2016, up from fewer than 500 in 2009.

“I thought, ‘Why don’t I just do this as insurance so I don’t miss the window?’” she says.

No guarantee

In truth, the window was already nearly closed. Fertility specialists encourage women who want to freeze their eggs to do so in their late 20s and early 30s, when they still have a healthy supply. Midway through gestation, a female fetus has 3 million eggs in each ovary. At birth, that number has dropped to 500,000. By puberty, a girl is down to 150,000 per ovary. At menopause that woman will have very few eggs left, and many will be riddled with genetic errors that occur with aging. The more DNA damage, the more likely an egg or embryo is to result in miscarriage, chromosomal abnormality, or no pregnancy at all.

It’s not clear why girls are born with more eggs than they could possibly ever use. Nor is it clear why the numbers drop so precipitously over the years, although genes seem to play a role. What is certain is that no one has figured out how to definitively extend fertility—yet.

Egg freezing is the closest we’ve come. Hyperstimulate a woman’s ovaries with hormone injections to produce more than the single egg released in a typical menstrual cycle. Retrieve those eggs with a needle in a quick surgical procedure. Then individually flash-freeze them using a method called vitrification, designed to prevent the formation of ice crystals, and immerse them in liquid nitrogen until they’re ready to be thawed. Ta-da—babies on ice!

When the American Society for Reproductive Medicine (ASRM) lifted the “experimental” label on egg freezing in 2012, the announcement appeared to herald an era of female empowerment. No longer would women have to sacrifice career for children; they could have it all, advancing professionally while banking their eggs for when they’d feel sufficiently established to risk derailing their careers to care for kids. If they hadn’t yet found Mr. or Ms. Right, they need not fear; they could simply freeze their eggs while continuing to search for the perfect partner.

Technology companies like Apple, Facebook, and others fanned the frenzy by covering the cost of egg freezing, about $10,000 per cycle, as an employee benefit.

In the seven years since, egg freezing has gone mainstream. If you were near Manhattan’s Bryant Park on June 20, you might have seen KindBody’s mobile fertility clinic, an RV in chic lemon yellow and white, parked next to an al fresco waiting room (a jute rug prettying up the sidewalk, saucer chairs, comfy poufs) where women could pop by for a fertility assessment after work. This consists of an ovarian ultrasound, a consultation with a fertility specialist, and bloodwork to test for anti-Müllerian hormone, which offers insight into “ovarian reserve”—the stockpile of follicles, or eggs, that remain inside the ovaries.

It’s a lot of attention for a technology that is far from a sure bet. Success rates for egg freezing are hard to determine, largely because the practice is so new that many women who’ve done it haven’t yet tried to fertilize their thawed eggs and get pregnant. What data does exist suggests that it’s a numbers game—predictably, the more eggs frozen at a younger age, the more likely at least one is to result in a baby.

“It’s not like I would discourage egg freezing. Women should be doing it because it’s the best option they have, but it is not an insurance policy,” says Christos Coutifaris, past president of the ASRM and a professor of obstetrics and gynecology at the University of Pennsylvania. “Insurance policies usually guarantee a payoff. In this case, there is no guarantee.”

There was nearly no payoff for Harrison, even though she produced 21 eggs, far more than would have been expected for someone her age—so many that the nurses high-fived her when she emerged from her anesthesia haze. “They were like, ‘It’s unbelievable,” says Harrison. “Of course, the doctor said you never know the health of the egg until it fertilizes, but that didn’t sink in. All I could think about was the number 21. I thought this was going to be a slam dunk.”

Harrison froze her eggs and went about her life. She met a man and fell in love, and when she was 43 and he was 47, they decided to start a family. Harrison tried to get pregnant, but the likelihood of conceiving at 43 is 5%, if that. After a few months of trying, she decided to thaw and fertilize her batch of frozen eggs, confident that her “insurance policy” would pay out. Then the phone calls began.

“Every couple of days, I would get a call from the lab saying, ‘You’re down to 10 eggs.’ Then eight. Then five. Then three,” says Harrison.

Her doctor recommended she do genetic testing on those three. Only one was genetically sound. “I was devastated,” she says. “No one prepares you for that emotion. No one prepares you for the highs and lows. No one prepares you that the number can get cut down so drastically.”

Fertility as a right

The prospect of extending fertility is of deep interest to a growing number of women. The birth rate for US women between the ages of 40 and 44 has been on the rise since 1985. The number of births to women 45 and older jumped 3% between 2016 and 2017. And the number of births to women 50 and older has also increased since 1997. This is not because women are staying fertile longer, but because more and more of them are trying to have kids later in life.

That trend has put pressure on researchers to come up with new ways to boost fertility. There’s a host of techniques in all stages of development, some benign (acai supplements), some invasive (pricking the ovaries to stimulate blood flow), some that sound like sci-fi (artificial gametes created from stem cells), and others that are downright weird (infusing the vagina with ozone).

“Men are certainly positioned to become fathers later in life, and no one has proposed banning that, so why should we prohibit women from becoming moms later in life?”

But what does it mean to extend fertility? Do we want to extend it a little—up to age 50, say—or a lot, enabling seventysomethings to give birth? Although women can’t easily conceive naturally with their own eggs much past 40, many healthy women in their 50s and even 60s can carry a pregnancy just fine.

However, studies suggest that women over 40 have an increased risk of pregnancy complications, including preeclampsia, gestational diabetes, and preterm birth. Most fertility clinics therefore set age cutoffs. “Even if we could take a woman’s own egg and make it perfect as technology evolves, there is an age at which you cross the line from acceptable to unacceptable risk,” says Alan Penzias, a reproductive endocrinologist at Boston IVF and chair of the ASRM’s practice committee, which sets policy for the organization. “Physiologically it can be done, but it shouldn’t be done. A woman’s body is not designed to be pregnant past her early 50s.”

But setting limits on who can get pregnant is tricky. “Men are certainly positioned to become fathers later in life, and no one has proposed banning that, so why should we prohibit women from becoming moms later in life?” asks Ruth Faden, founder of the Johns Hopkins Berman Institute of Bioethics. She sees the issue as just the latest salvo over reproductive rights in the US, “respecting the rights of women to control their own reproductive stories.”

Still, it’s undeniable that from a purely physiological perspective, pregnancy is the purview of the relatively young. “I always remind people that medicine has been able to lengthen life span, but somehow women’s reproductive life span hasn’t changed,” says Mandy Katz-Jaffe, scientific director at CCRM, where Harrison was treated. The ovaries are the fastest-aging organ, doing their job only from puberty to menopause. People who live longer, healthier lives have more time to build their families, but women’s bodies haven’t evolved to easily allow that.

Successfully extending women’s fertility would have benefits beyond childbearing itself, though. “I don’t wake up in the morning with my goal to help women have babies when they’re 70,” says Francesca Duncan, who runs the Center for Reproductive Science at Northwestern University. Identifying ways to delay ovarian aging, she notes, would cause the ovaries to produce estrogen for longer, which is good for women’s health: among other benefits, it offers protection against heart disease, the leading cause of death for women.

Duncan is also an adjunct professor at the newly established Center for Female Reproductive Longevity and Equality, part of the Buck Institute for Research on Aging. The center launched last year to “address an inequality which has existed throughout human history: men can reproduce throughout their life span; but women’s fertility begins to decline in their early 30s.”

“In my head I was thinking, ‘God, I wish I could change the narrative on my reproductive situation!’” Shanahan recalls. “And then I thought, ‘Wow, maybe I can.’”

The center is the first place to bring together scientists working on aging in general and female reproductive aging in particular, and specifically fertility. It’s the brainchild of Nicole Shanahan, a lawyer who became aware of this reproductive inequity at the age of 29, when a fertility checkup revealed she had hardly any active follicles. She tried to bank eggs and embryos for IVF, but each month she had developed a new ovarian cyst that prevented the treatment. “Following the arc I was on, I was quickly going to be in menopause in my mid-30s,” says Shanahan, who is Google cofounder Sergey Brin’s girlfriend. “There was no explanation as to why.”

Growing up poor in Oakland, the daughter of an immigrant mother, Shanahan, now 33, was encouraged to dream big: to go to college and law school, get married, and have a career, a house, and a family. “It was eye-opening to me that there are biological factors that would limit that dream,” she says.

Through her work as a lawyer, Shanahan found herself in 2017 with Moby, Goldie Hawn, and other Hollywood glitterati at a meeting on “health longevity” in the living room of TV producer Norman Lear. In a corner, Shanahan multitasked, checking her Flo app to see if she was ovulating while listening to Victor Dzau, head of the National Academy of Medicine, talk about changing the narrative on aging. “In my head I was thinking, ‘God, I wish I could change the narrative on my reproductive situation!’” she recalls. “And then I thought, ‘Wow, maybe I can.’”

“I felt a great sense of injustice,” says Shanahan. “At a time in history when we’re questioning everything, there needs to be room for consideration of this.”

She continued putting out feelers until the Buck Institute expressed interest. The new center is in the process of hiring faculty and spreading the word about its mission. Shanahan originally gave $6 million to the new center through the Sergey Brin Family Foundation and is increasing her commitment through the Bia Echo Foundation, which she recently started to focus on issues of women’s reproductive longevity and equality, criminal justice reform, and protecting the health and habitability of the planet. Bia is the Greek goddess of raw energy; Echo is the name of her daughter, whom she and Brin welcomed in November. After years of failed fertility treatment, they conceived naturally.

Tough decisions

After going from 21 eggs to one, Michele Harrison lucked out. On July 13, 2015, she and her husband, John, became parents to Ellie, who is now four and has bright blue eyes, dirty-blond hair, and chubby cheeks. Harrison, 44 when her daughter was born, has moments when she wonders what it would be like for Ellie to be a big sister, but she knows it’s out of the realm of possibility. “I still get twinges when I see people in their 40s having another baby,” she says.

Photograph of Michele Krumper and her daughter sitting out by a lake
Benjamin Rasmussen

The quest to extend women’s fertility will march on, however. Egg freezing will continue to be used as a pressure relief valve for women who aren’t ready to have children. More women will confront this critical and expensive choice as clinics adjust their marketing to target twentysomethings.

As head of the ASRM’s practice committee, Alan Penzias thinks this is overkill—in theory. “Don’t even think about talking to me about egg freezing,” his daughter cautioned him when she turned 24. He responded not as a physician but as someone with a desire to be a grandfather one day: “I have no interest in talking to you about this … well, maybe a little interest.”

Even as it becomes biologically more feasible to prolong fertility, not all women are going to be clamoring to have babies later in life. In June, I cuddled my two-week-old niece, six pounds of vulnerability and potential in a spangled hot-pink onesie. I loved holding her, but I was equally glad to hand her back. I’m closer to 50 than 40. With my oldest child two years away from finishing high school, I’ve been there and done that. But for women my age who feel the right time to become a mother is now, it’s good to know that there are smart people working to level the reproductive playing field.


Bonnie Rochman is a freelance journalist in Seattle. Her latest book is The Gene Machine.

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