Three in four IVF babies now born from frozen embryos
UNSW Sydney
Key Facts:Modern approaches in Australian fertility treatments continue to improve pregnancy success while reducing risks for mothers and babies.
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Australians undergoing IVF now have a better chance of taking home a baby than they did just five years ago, as new data from Australia and New Zealand show treatment has evolved to become not only increasingly effective but also safer for mothers and babies.
The latest Australian and New Zealand Assisted Reproduction Database (ANZARD) report recorded almost 114,000 IVF treatment cycles in 2024, resulting in more than 20,900 babies.
This equates to one in five initiated cycles leading to a live birth.
“Fertility treatment is playing an increasing role in helping families grow,” says Professor Georgina Chambers, Director of UNSW’s National Perinatal Epidemiology and Statistics Unit (NPESU) and lead author of the report.
She says newer freezing practices such as embryo vitrification have significantly improved the chances of embryos surviving the cryopreservation process.
She also says there is a growing use of ‘freeze-all’ IVF cycles, where all embryos are frozen and then transferred in a later cycle.
Today, around 70% of embryo transfers involve a frozen embryo.
Frozen the new norm
A common assumption is that eggs are collected, used to create embryos, and that one embryo is transferred straight away.
Instead, embryo transfers are often intentionally delayed – allowing a woman's body to recover from ovarian stimulation, with greater flexibility to transfer embryos under more favourable conditions.
The report highlights a clear shift in IVF practices, where almost half (44.5%) of initiated fresh cycles resulted in all eggs or embryos being frozen for future use. Five years earlier, it was only 31.6%.
In the five years from 2021 to 2024, live birth rates per embryo transfer rose – from 31.2% to 33.3% for frozen embryos, compared with a smaller increase from 25.4% to 26.2% for fresh embryos.
“Cryopreservation has long been a major focus of fertility care in Australia and New Zealand,” says Dr Petra Wale, President of the Fertility Society of Australia and New Zealand (FSANZ), which funded the ANZARD report.
She says alongside single embryo transfer, the process allows clinics to reduce the risks associated with multiple pregnancies while giving patients the best possible chance of building a healthy family.
“Cryopreservation is now so successful that clinics can plan embryo transfers for the best time in a patient’s treatment and consider their longer-term hopes for family size,” Dr Wale says.
“The data shows why this approach is becoming more common: it can improve the chance of success while supporting safe treatment for patients.”
Improved safety
The increased use of single embryo transfer rose to 95.4% in 2024 from 93% in 2020, reducing the risks associated with multiple pregnancies.
A continued emphasis on treatment safety helped keep the multiple birth rate steady at 2.2%.
Demonstrating the safety of IVF practice in the region, of the 20,918 babies born from IVF treatment in 2024, 82.5% were full-term singletons of a healthy birthweight. By comparison, 92% of all babies born in Australia had a normal birthweight.
“Single embryo transfer is one of the most important advances in IVF,” says Dr Simon McDowell, FSANZ Vice President, who is an advanced fertility and hormone specialist.
“Australia and New Zealand have always been world leaders in the field with our multiple births rate being below 5% for over a decade,” Dr McDowell says.
“We have been able to significantly reduce the health risks associated with multiple pregnancies while increasing success rates.”
Helping more families
The report highlights steady improvements in treatment outcomes.
The uptake of IVF in 2024 had a modest increase in cycles – up 1% from 2023.
Live birth rates after embryo transfer rose from 28.9% to 31.1% in just five years.
“IVF is not only becoming more effective, but continues to support a diverse range of families,” Prof. Chambers says.
“14.4% of cycles were undertaken by single women and 4.6% by same-sex female intended parents.”
A further 271 surrogacy or gestational carrier cycles were performed.
A journey, not an attempt
IVF is often more than just a single attempt. Of the 43,849 women who started IVF for the first time between 2021 and 2022, 37% had a baby in their first complete IVF cycle.
However, by six complete cycles most women continuing treatment achieved a live birth, with the chance of a baby increasing to 57.6% by the sixth complete IVF cycle. When women who discontinued treatment were accounted for, the estimated chance of having a baby after six complete IVF cycles was almost 77%.
“For many patients, IVF involves more than one cycle, with each cycle reflecting a significant emotional, physical and financial journey,” Prof. Chambers says.
“However, these data show that the chances of a baby are encouraging even after a number of failed attempts,” she says.
“Female age plays a big role in the chance of success – and educating couples about this is important.”
For example, after three complete IVF cycles using their own eggs, women aged under 30 had the highest chance of achieving IVF success with a cumulative live birth rate of 71%. This fell to 21% for women aged 40–44, and 3% for women aged 45 or more.
“These numbers emphasise the reality that IVF success is often achieved over multiple cycles, with complex and sometimes challenging journeys behind each positive result,” says Dr Wale.
Data from ANZARD was also used to develop Australia’s first, independent egg freezing calculator, YourEggFreeze. The government-funded tool supports decision making about whether to freeze eggs as well as help those who already have frozen eggs better understand misconceptions as well as their future chances of success.
The tool, hosted on the YourIVFSuccess.com.au website, was co-developed in partnership with IVF clinicians, nurses, and counsellors.
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Melissa Lyne
UNSW News & Content