Health & wellness


Trying to pause the biological clock

Increasingly, women who aren’t ready for children are freezing their eggs for later use, though it’s not always an easy decision

A laboratory manager at Fertility Centers of New England views an egg through a microscope.
A laboratory manager at Fertility Centers of New England views an egg through a microscope.

For Deb, a 45-year-old consultant in Boston, it was a back-up plan that’s becoming a reality.

For Kathleen, a 37-year-old graduate student, it’s an uncomfortable reminder that her life hasn’t unfolded quite how she’d hoped.

And for Shana, a 34-year-old New Yorker, it’s an expensive insurance policy – one she hopes she’ll never have to use.


Egg freezing is growing in popularity among women who, for whatever reason, are not ready to have children, but want to preserve the option for when they are.

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The scientific advances that have made egg freezing possible come at the same time that social trends have led to later marriage, delayed childbearing, and lower birth rates.

Last year, the American Society for Reproductive Medicine (ASRM) lifted the procedure’s “experimental” label, which has led to wider availability, although insurance does not cover the procedure.

Now more women are asking themselves: Should I freeze my eggs?

As Deb, Kathleen, and Shana’s stories attest, it is a complicated and intensely personal question, with no easy answer. Simply asking the question forces women to confront their hopes and disappointment, deeply ingrained beliefs about family, and ultimately, the uncertainty over whether egg freezing will actually allow them to achieve their goals.

Lab manager Wayne Caswell tops off a cryotank containing frozen embryos.


“It was almost an acknowledgement that I didn’t want to make,” said Kathleen, a Boston woman who did not want her last name used to protect her privacy. “I wanted to have been married by now. I wanted to have started a family, I didn’t want to expose myself to doctors and nurses and huge withdrawals of money just to think of having a child one day.” Kathleen paid nearly $10,000 to have eggs frozen this year.

“I don’t have regrets,” she said, before pausing. “Yet . . . talk to me in another six years.”

The ability to freeze eggs is fairly new.

Scientists have been successfully freezing sperm since the 1950s, and embryos (fertilized eggs) since the 1980s, but freezing eggs posed a problem. The problem: Ice crystals. As the largest cell in the body, eggs contain genetic information, but they also contain a lot of water. That’s troublesome, because it means that, when frozen, ice crystals can form that act as “daggers” that can destroy the egg’s structure, said Michael Tucker, an embryologist and IVF Laboratory Director at Fertility Centers of New England. Even if a frozen egg could successfully be thawed, more often than not, the freezing and thawing process made it tough for the sperm to successfully fertilize the egg.

With these barriers, interest in egg freezing was limited. But in the early 1990s, a scientific advance moved the technology forward.


A technique called intra-cytoplasmic sperm injection started as a way to help men with infertility become biological fathers. It’s a delicate process that uses microscopic tools to take a single sperm and inject it directly into an egg. The technique could be applied to thawed eggs, allowing them to be fertilized reliably.

But ice crystals still posed a problem, and that prevented reality from living up to expectations.

“People were really expecting egg freezing to be super consistent. Biological clocks were going to be turned back,” Tucker said. “But what was available was very different than the perception.”

A canister containing frozen embryos.

Then came the second key advance. In Italy, researchers had long been working on egg freezing — driven by religious aversion to freezing multiple embryos. There, scientists started to routinely apply an ultra-rapid freezing process called “vitrification” — the word literally means ‘to make into glass’ — whereby eggs were chilled so quickly that the ice crystals didn’t have time to form. Whereas slow freezing drops an egg’s temperature about a degree a minute, Tucker said, vitrification takes seconds to bring the egg from room temperature to the temperature of liquid nitrogen. This, said Tucker, was the “game changer.”

By the early 2000s, the procedure was still not widely known about among women who might have an interest, and doctors were slow to recommend to it.

Deb, the consultant in Boston, heard about egg freezing for the first time about a decade ago. She was 35 at the time, unmarried, and knew she wanted to have a family someday. So she went to her gynecologist with the question: Should she freeze her eggs?

Her doctor responded negatively, instead counseling her that she’d be better served by using the time and energy to find a relationship.

She did. But after five years, and single once again, Deb returned to the idea of freezing her eggs. She still wanted a child, but not without a partner. It was 2009 and at 40, she was pushing the age limits of when physicians consider freezing eggs to be worthwhile.

Once a woman decides to freeze her eggs, another question comes into play: When is the right time?

That calculation is ultimately a balance between what’s ideal and what’s realistic, but most experts agree on a few guidelines. Reproductive endocrinologist Joseph Hill of Fertility Centers of New England says he’d optimally freeze eggs before age 30, but, if not, before 35 if possible, and definitely before age 38. As women age, their eggs decline in number and quality. Not only is it harder for women to get pregnant after that point, but older eggs are more likely to have chromosomal abnormalities, and are more likely to result in miscarriage.

“The reality is that the best time to freeze eggs would probably be the 20s to early 30s,” said Elizabeth Ginsburg, the medical director of assisted reproductive technologies at Brigham and Women’s Hospital, who notes that once eggs are frozen, there isn’t a “shelf-life.”

“But women aren’t starting to feel time pressure until later,” she said.

Even with these caveats, most reproductive specialists will attempt the procedure — if testing demonstrates that the ovaries are still able to produce eggs — up until a woman is in her early 40s.

“In those cases, I lower their expectations,” said David Ryley, a reproductive endocrinologist at Boston IVF. “I tell them, ‘I understand why you’re doing this. But there’s a better chance it won’t work than it will.’ ”

Ryley notes that most studies of egg freezing were done in women who are younger than 35, many of whom froze eggs to donate, rather than to prolong their own child-bearing window. These studies — which led to the ASRM’s approval of egg freezing — suggested fertilization and pregnancy rates using frozen eggs that were similar to rates of IVF with eggs that weren’t frozen.

And, reassuringly, the studies haven’t shown an increase in abnormal births. More than 2,000 babies have been born from frozen eggs, according to Ginsburg.

But it’s hard to say precisely how these data will apply to older women. The ASRM cautions against overly enthusiastically applying these findings to “women in the later reproductive years.” The society’s paper on the topic, published in January, reads: “Marketing this technology for the purpose of deferring childbearing may given women false hope and encourage women to delay childbearing.”

That’s why doctors are quick to note that egg freezing will only preserve the fertility you have at the time the eggs are frozen; it can’t turn back the clock. Too often, infertility experts say, they’ll see patients who’ve assumed that because they appear younger than their biological age, exercise regularly, eat well and haven’t reached menopause, that somehow they’ve avoided the age-related decline in fertility.

But discussions about whether, and when to freeze can be tricky. The measure of success might not be gauged until years in the future, if and when a woman successfully uses her frozen eggs. While certain centers have published success rates, there’s no national data source for success rates, as there is for IVF.

Thomas Toth, who directs the In Vitro Fertilization Unit at Massachusetts General Hospital, takes a conservative approach when discussing potential outcomes of egg freezing.

“Because there are just pockets of people doing this around the world, there just aren’t big numerators or denominators,” he said. “And techniques might be different in different hands.”

As popularity grows, and more clinics offer the pricey procedure, Hill, from Fertility Centers of New England, warns of a “buyer beware” market. “Now, the banner’s out,” he said.

The increasing buzz might also mean that interest in the technology is filtering down to younger women. In the past year, Nicole Noyes, codirector of New York University’s Fertility Center, said she has seen more women in their early 30s undergo the procedure. This hasn’t always been the case: A recent study conducted by the center described the nearly 500 women who’ve undergone egg freezing there from 2005 to 2011 and the majority were between 36 and 41 years old. And a survey of women who froze their eggs at an average age of 37 found that a majority would do it again if they could, but wished they had done so at a younger age.

At 40, Deb’s doctors cautioned her that even if they were able to retrieve eggs, they’d have a slim chance of turning into a pregnancy. But for Deb, that chance was worth it. She went through a cycle of hormones, giving herself a shot each day for about 10 days to rev up her ovaries. But when it came time to extract the eggs with the ultrasound-guided needle, her doctors were only able to retrieve four.

Doctors will generally recommend that at least 10 eggs are frozen, if possible, so Deb “pushed and pushed” to undergo one more round of hormones. By then, she was 41. She borrowed money from friends and family to pay a bill that ultimately came to $15,000. This time, six eggs were frozen. A few weeks later, she received a picture of her eggs in the mail.

Now Deb is 45. She’d hoped not to have a child alone, but relationships have come and gone. She spent last year trying to get pregnant via artificial insemination with donor sperm and her own 44-year-old eggs — a far less pricey procedure than using the frozen eggs — but the attempts failed.

After “a little break to catch my breath and get my bearings,” she’s planning to give her frozen eggs a try. This is her Plan B. She’s not certain whether she’ll be emotionally or financially able to face Plan C — adoption — if this doesn’t work.

“I don’t know how I’m going to feel,” Deb says. “Every step of the way, I’ve had to rethink everything. I know I’m getting older. Do I want to have a baby at 50?”

Deb urges younger women to freeze eggs if they’re considering the procedure. She wishes she had been similarly encouraged when she first asked the question at 35.

“When I talk to women, I just say do it,” she says. “No one knows how life is going to turn out.”

A few years ago, Shana Randhava and a group of her business school friends decided, semi-seriously, that if they weren’t pregnant by age 35 they would freeze their eggs. A few friends went through with it. Her brother’s wife had a baby, and Randhava started to think more seriously about the procedure.

She was relieved when doctors were able to extract 19 eggs and freeze 15 of them after one cycle of hormones.

While friends had given her a rundown of what to expect during the procedure — from what medications she’d take, to the fact that she’d get a separate bill for the anesthesia — she wasn’t so prepared for the emotion of the experience. In the time it took to give herself hormone shots, wondering about who’d pick her up from the hospital, Randhava found unexpected time for reflection.

“I do want to have kids, and I’m not getting any younger. You’ve got to be responsible, at the end of the day, for the choices you make,” she said. “This, alone, isn’t going to solve it all. I need to take some steps to fix the other things that are going on.”

Randhava, a New York banker, is now securing a new job, tired of the long and unpredictable nights she’d worked since business school graduation in 2007. Freezing eggs wasn’t the catalyst for the change, but it’s helped shift her priorities.

“I hope I wasted the money. If I did, I’m OK with that,” she said. “But it’s kind of nice to know they’re there — 15 little eggs waiting for me, if I need them.”

Dr. Daniela J. Lamas can be reached at