18 October 2023

Frozen is as good as fresh: New Australian study is good news for women who are thinking about freezing their eggs

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A new Australian study has found pregnancy success rates for women whose eggs have been frozen are similar to those using fresh eggs.

The study of more than 30,000 eggs collected by Melbourne IVF over 10 years shows egg freezing and later thawing leads to survival rates of 92% with fertilisation rates around 65%, which is similar to the fertilisation rate when using fresh eggs.

The retrospective study included 3,280 elective egg cycles from January 2013 to December 2022.

The results of this major study are being presented at the American Society for Reproductive Medicine (ASRM) Congress, one of the world’s biggest fertility research conferences.

The study’s author says the outcome is encouraging news for women who are thinking about freezing their eggs.

John Stevens, Director of ART Laboratories at Melbourne IVF, said, “If a woman elected to freeze her eggs at the age of 35 and came back to use her frozen eggs when she was 41 years old, the pregnancy success rates of the thawed eggs will be similar to that of a 35-year-old using fresh eggs.

Dr Fleur Cattrall, Medical Director at Melbourne IVF explains: “We know that egg quality deteriorates with age. By freezing eggs, it pauses ageing. This study provides reassurance to patients that elective egg freezing pregnancy results are close to that of patients using fresh eggs.”

John Stevens cautions that, as with fresh eggs, not all thawed eggs will fertilise and became embryos.

“The goal of this retrospective review is to help manage patient expectations when it comes to elective egg freezing,” John Stevens said.

“It’s best to have a good number of frozen eggs. The more eggs collected, the greater the chance there is of finding at least one good egg with the potential to become an embryo and a baby.  

“The guidelines that we give patients are that under the age of 35, seven or more mature eggs will need to be frozen for a 50% chance of a live birth. If the patient is aged 35 or over, 12 or more mature eggs will be needed to achieve a 50% chance.” 

Melbourne IVF’s fertility specialists carefully counsel egg freezing patients and personalise this counselling taking into consideration the patients age and unique fertility factors. 

John Stevens explains that not all IVF clinics will routinely achieve a survival rate of 92% when they are freezing eggs using the ‘fast-freeze’ vitrification method.

“It takes skill and training to vitrify eggs and achieve a 92% survival rate. This high result wouldn’t be expected from a new embryologist. Egg vitrification and egg warming is one of the very last procedures in which an embryologist is trained due to its complexity,” he said.

“We recommend women aim to freeze their eggs with an IVF clinic that has experience. The recent advancements in egg freezing technology means IVF success rates using frozen eggs are now similar to pregnancy rates of age-matched women undergoing IVF using fresh eggs.”

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