Freezing eggs when younger is better for women delaying motherhood

Francesca Gavins

Progress Educational Trust

25 June 2022

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[BioNews, London]

Older women have a better chance of pregnancy from IVF with previously frozen eggs compared to freshly collected eggs, according to a new study.

Research from New York University (NYU) examined the rates of live birth from women using their own frozen eggs in fertility treatment. They found that success rates were comparable to IVF results for patients using freshly collected eggs, when matched by age at egg collection.

'Our findings shed light on the factors that track with successful births from egg freezing,' said Dr Sarah Druckenmiller Cascante from NYU Langone Fertility Centre. 'A better understanding of the live birth rate from egg freezing for age-related fertility decline is necessary to inform patient decision-making.'

The study was a collaboration between the Langone Fertility Centre and the NYU Grossman School of Medicine, who reviewed data from 543 patients who froze and subsequently thawed their eggs to use in treatment between 2005-2020.

The patients had an average age of 38 at the start of treatment, and 42 when the eggs were thawed for use. Between them they underwent 800 egg freezing cycles, 605 egg thaws, and 436 embryo transfers. As a result, 211 babies were born – a birth rate of 39 percent per patient, and some patients had more than one child.

The age at the time of the freezing eggs and the number of eggs thawed were predictive of the live birth rates: no live births were seen in patients whose eggs were collected at age 44 or older. Women who froze eggs before they were 38 and thawed at least 20 eggs had the highest chance of a live birth at 70 percent. For patients who met one but not both criteria, it was 50 percent.

This compares to a live birth rate of below 20 percent in women aged 40 who use their own freshly collected eggs.

Because the number of eggs thawed was a predictor of success, patients who had two cycles of egg collection were more likely to have a successful pregnancy. The length of time the eggs were frozen did not affect success rates.

'Importantly, our study is based on actual clinical experience,' said Dr Cascante, 'rather than mathematical modelling with limited data, which is most of what has been published on the chance of births from egg freezing thus far.'

The authors added that further studies are needed in patients below 35 years and with a larger number of patients across different centres and geographical areas.

The results were published in Fertility and Sterility.

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