Everything you need to know about freezing your eggs and the best age to do it

Research from a leading US fertility clinic has found that a woman's chance of a live birth from egg freezing is linked to her age at the time of retrieval. Irish medics say early to mid-30s is the ideal time to undergo the procedure but warn the results cannot be guaranteed 

“We tell every woman who enquires about egg freezing that she cannot be certain her eggs will produce a baby in the future,” says Dr John Waterstone, medical director of Waterstone Clinics.

What if women could press pause on the ticking of their biological clocks? What if a fertility treatment gave them extra time to build a career and find a partner before they settled down to start a family?

Egg freezing seems to offer this possibility, but new research suggests that we need to manage our expectations. Frozen eggs doesn’t always lead to pregnancy and a baby.

“We tell every woman who enquires about egg freezing that she cannot be certain her eggs will produce a baby in the future,” says Dr John Waterstone, medical director of Waterstone Clinics.

Since the 1980s, egg freezing has been an option for women diagnosed with early menopause or where cancer treatment requires removing ovaries or risks damaging eggs. In the early 2000s, the technology had become much more effective and fertility clinics started offering the procedure to healthy women. This marked the beginning of social egg freezing, where women not yet ready to have children freeze eggs until the time is right for them to get pregnant.

New York University’s Langone Fertility Centre was one of first clinics to offer social egg freezing.

It has now published data from all the women who have thawed their eggs over the past 15 years to establish an overall success rate.

The centre’s study looked at 543 women who went through 800 egg-freezing cycles, of which 605 were thawed, 436 resulting in embryo transfers and found the overall chance of a live birth was 39%.

This tallies with another recent study carried out by the Boston IVF Fertility Clinic. Of 921 women who had frozen eggs up to October 2020, 7.4% had used them, with a live birth rate of 32%, or a one in three chance of having a baby.

However, closer examination of the NYU study reveals more encouraging findings. If women were younger than 38 when they froze eggs, their chance of a live birth rate rose to 51%. If that same woman thawed 20 or more eggs, chances soared to 70%.

“This study confirms that the age of a woman when she uses her eggs to try for a baby is not what determines her chances of success,” says Dr John Kennedy, medical director of Thérapie Fertility in Dublin. “The age at which she freezes her eggs and how many she freezes is what matters.”

He says it’s a numbers game.

“At 32 years old, the likelihood of any one frozen egg becoming a live birth is 3.5% at its highest. That’s because most eggs don’t make good embryos. Your chances at 40, when your egg quality has deteriorated, are 1%. At first glance, there’s not much between 3.5% and 1% but if you’re working with 20 eggs, it’s the difference between a 70% chance of success and a 20% chance.”

Egg quality deteriorates with age

The fact that egg quality deteriorates with age needs to be made absolutely clear to women, says Dr David Crosby, medical director of the Merrion Fertility Clinic in Dublin.

“This procedure is not without cost so it’s important that women are advised of their chances of success,” he says. “We tell our patients that age is the single most important determinant of reproductive outcome. If a woman freezes her eggs after the age of 35, the chances of a successful live birth are substantially reduced. Even before that age, there are no guarantees of success.”

Women whose health insurance doesn’t include egg freezing can expect to pay approximately €3,000 for a single round of egg freezing. In fact, they’re likely to pay double that as, according to Dr Kennedy, the majority need at least two rounds to retrieve enough eggs to give a cumulative birth rate of more than 50%.

Because of this financial cost and its related emotional toll, the Waterstone Clinic takes a cautious approach to egg freezing.

“We dissuade women who are older than 37 from considering it,” says Dr Waterstone. “We’ll only go as high as 38 if their egg numbers seem reasonably good.”

Determining those numbers is the first step in the egg-freezing process. It’s done through a combination of blood tests and ovarian scans.

“We don’t always get it spot on, but this information gives us a realistic idea of how many eggs we can expect to retrieve in a single cycle,” says Dr Kennedy.

If they decide to proceed, women then take potent fertility drugs over a two-week period to stimulate their ovaries into producing multiple healthy eggs. Those eggs are then collected in a short surgical procedure before being frozen and stored until the woman decides to use them. There’s an annual charge of approximately €300 for this storage.

Even though egg freezing isn’t a guarantee of pregnancy, demand is increasing. At Waterstone Clinic, it’s a gradual increase.

“We completed 61 cycles last year and we’ve done 70 so far this year,” says Dr Waterstone.

The rate of increase is higher at the Merrion Fertility Clinic.

“Demand for the procedure doubled between 2020 and 2021 and we’ve performed 124 procedures to date this year,” says Dr Crosby.

Dr Kennedy is seeing the same upward trend.

“Our clinic only opened last year but we’re already carrying out between 20 and 30 egg-freezing cycles a month,” he says.

The pandemic is one of the factors contributing to this upsurge in interest.

“It made everyone pause and reflect on their lives and what was important to them,” says Dr Waterstone. “It made many single women who didn’t have a partner but who were interested in having children in the future realise that that’s what they wanted and that now was the time to do something about it.”

An increase in awareness is another contributing factor, according to Dr Crosby.

“The initial technology was designed to freeze eggs for women who had an urgent need to do so because of cancer or a family history of premature menopause,” he says. “Now, women are becoming more informed and are freezing their eggs to extend their biological window.”

Dr Kennedy hopes this fertility awareness continues to increase.

“I’d like to see more women getting themselves checked out at a younger age and then taking ownership and agency over their fertility,” he says. “A few years ago, the average age of a woman freezing her eggs was 38, which as this study shows is probably too old to have a high chance of success. However, in our clinic, that number has reduced to 35 and I’d love to see it go even lower. Ideally, we’d like women to freeze their eggs at 34 or younger.”

Irish conception numbers low

The first Irish baby to be conceived using a frozen egg was born in 2016 and while there are no statistics available on those born since, all three fertility doctors agree that the number remains low.

One is that clinics here were slow to offer the service.

“We’ve only been offering egg freezing at Waterstone Clinics for the past three years,” says Dr Waterstone. “We wanted to be sure that it worked first as we were worried we might be raising false hopes for women. Of the eggs we have frozen, none have been thawed yet.”

Another reason is the natural lag between women freezing their eggs and coming back to thaw them.

“That’s the whole idea of social egg freezing,” says Dr Kennedy. “It gives women time so there’s always a period of years before they come back to use their eggs. Personally, I’ve only seen a handful of live births from egg freezing.”

The reported international data, based on a 2018 Spanish study, “suggests that to date, only 12% of women have used their frozen eggs,” says Dr Crosby.

A third reason is that some women go on to meet a partner and conceive naturally, which means their eggs are never used.

For millennia, women had very little control over their fertility. Some became pregnant by choice, some by accident. Others struggled to conceive while others didn’t meet the right man at the right time. Dr Waterstone would like to see egg freezing become a way in which they can exercise more control over their choice to have a baby.

“If a woman is single, in her early to mid-30s and wants to have a baby one day, she can now be proactive and do something about it,” he says. “She can freeze her eggs in the hope that when a partner does come along, she has the chance of having a baby with him. Or she can try to have a baby on her own using donor sperm.”

Egg freezing isn’t a failsafe insurance policy. Studies and statistics show that it doesn’t guarantee the birth of a baby. But it does freeze your fertility at a particular moment in time so that you can try for a baby when the moment is right for you to start a family.

“By doing nothing, your fertility levels will continue to decline, and the time will come when you have zero chances of having a baby,” says Dr Kennedy. “Freezing your eggs isn’t a guarantee of a baby but it does preserve fertility levels and gives you some chance of success.”

"It's such a huge weight off my mind"

Anna Monaghan

Anna Monaghan, an IT manager from Blanchardstown in Dublin, was 34 when she froze her eggs.

A conversation with a doctor prompted her decision. “During an operation to remove my appendix when I was in my early 20s, the surgeon spotted signs of polycystic ovarian syndrome, and I was booked in for regular check-ups to keep an eye on that,” she says. “It was during one of those check-ups that the consultant asked me about my thoughts on having children.” 

Monaghan had been single for a few years at that point. “I wanted children, so I’d decided that I’d give myself another few years to meet a man and do it on my own if a man didn’t come along,” she says.

Her consultant suggested egg freezing. “He said I’d have a better chance of success with younger eggs,” says Monaghan. “So I followed his advice and booked into a fertility clinic.” 

A nurse took her medical history, and she underwent a series of blood tests and scans. “Everything looked good, so I was advised to come off birth control and come back in a few months,” she says.

She returned in January this year and was prescribed a combination of tablets and injections to stimulate her ovaries into producing eggs. She had scans every second day, and at the end of the two-week process, she froze 23 eggs.

 “I thought I’d have to do two cycles to get that many, so I was delighted,” she says. “It’s such a huge weight off my mind.” 

Monaghan found the process straightforward. “Basically, I had to take tablets, give myself injections, undergo a short procedure and then rest,” she says. 

“The only side effect was that my short-term memory went during the medication stage, and I kept repeating myself. I was also worn out afterwards and had to take a few days to rest. But it wasn’t too much of an ordeal for the peace of mind it’s given me. I hope not to have to use my eggs but it’s great to know they’re there if I need them.”