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HomeEditor's PickFrozen eggs more efficient than IVF for older women – US study

Frozen eggs more efficient than IVF for older women – US study

The largest US report of elective fertility preservation outcomes to date found that 70% of women who froze eggs before they were 38 – and thawed at least 20 eggs at a later date – fell pregnant and gave birth.

In comparison, and using fresh eggs or embryos from women trying to conceive, at age 40 fewer than 30% undergoing in vitro fertilisation (IVF) become pregnant and fewer than 20% gave birth to live babies as a result, according to statistics gathered by the US Centres for Disease Control and Prevention from the nation’s nearly 500 fertility clinics.

The findings were based on 15 years’ of “real life” frozen egg thaw outcomes for women who had delayed childbearing and faced natural, age-related fertility decline.

Led by experts at NYU Grossman School of Medicine and the NYU Langone Fertility Centre, the study also found that a considerable number of the women studied had more than one child through egg preservation. In total the study reports 211 babies from egg freezing.

Egg freezing and thawing at a later date provides a higher pregnancy success rate than using fresh embryos during assisted reproductive technology, said the study authors.

“Our findings shed light on the factors that track with successful births from egg freezing, which include careful screening of embryos to be thawed and implanted,” said study lead author Dr Sarah Druckenmiller Cascante, fellow in the Division of Reproductive Endocrinology and Infertility, within the Department of Obstetrics and Gynaecology at NYU Langone.

“A better understanding of the live birth rate from egg freezing for age-related fertility decline is necessary to inform patient decision-making.”

“Importantly,” she added, “our study is based on actual clinical experience 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.”

Specialists within the NYU Langone Fertility Centre have been pioneers in the development of egg freezing technology, with the first baby born through via egg freezing at NYU Langone in July 2005. The centre has seen almost triple the number of women starting egg freezing cycles in 2022 in comparison to 2019. As this trend increases, more data is needed to inform patients who seek to secure their reproductive futures.

Methodology

Within the study, 543 patients participated with an average age of 38-years-old at the time of the first egg freeze, which is older than the optimal age to freeze eggs (35 or younger). These patients underwent 800 egg freezing cycles, 605 egg thaws, and 436 embryo transfers between 2005-2020.

The investigation found that overall, 39% of women between 27-44 years old, with a majority between 35-40 years old at egg freeze, had a least one child from their frozen eggs, which is comparable with age-matched IVF outcomes. Across all ages, women who thawed more than 20 mature eggs had a 58% live birth rate, which was unexpected as this group included patients past their reproductive prime.

In fact, 14 patients who froze eggs at the age of 41-43 successfully had children from their frozen eggs. As noted, women under 38 who had 20 or more mature eggs thawed achieved a 70% live birth rate per patient. The length of frozen egg storage did not change the success rate.

Results also showed that pre-implantation genetic screening with embryos from frozen and eventually thawed eggs resulted in lower miscarriage rates and higher live birth rates per transfer. Such screening also allows for single embryo transfers, yielding singleton pregnancies, which are safer for both the mother and child, say the authors.

“Our results provide realistic expectations for those considering oocyte preservation, and demonstrate that egg freezing technology empowers women with improved reproductive autonomy,” says study senior author Dr James Grifo, director of the Division of Reproductive Endocrinology and Infertility and the NYU Langone Fertility Centre.

Grifo, also a professor in the Department of Obstetrics and Gynecology at NYU Langone, cautioned that the study was limited by the number of patients. Future larger studies are under way to increase the data set from which patients can benefit and model their expected success rates.

Study details

Fifteen years of autologous oocyte thaw outcomes from a large university-based fertility centre

Sarah Druckenmiller Cascante, Jennifer Blakemore, Shannon DeVore, Brooke Hodes-Wertz, Elizabeth Fino, Alan Berkeley, Carlos Parra, Caroline McCaffrey, James Grifo.

Published in Fertility and Sterility on 18 May 2022.

Objective
To review the outcomes of patients who underwent autologous oocyte thaw after planned oocyte cryopreservation.

Design
Retrospective cohort study.

Setting
Large urban university-affiliated fertility centre.

Patient(s)
All patients who underwent ≥1 autologous oocyte thaw before December 31, 2020.

Main Outcome Measures
The primary outcome was the final live birth rate (FLBR) per patient, and only patients who had a live birth (LB) or consumed all remaining inventory (cryopreserved oocytes and resultant euploid/untested/no result embryos) were included. The secondary outcomes were laboratory outcomes and LB rates per transfer.

Results
A total of 543 patients underwent 800 oocyte cryopreservations, 605 thaws, and 436 transfers. The median age at the first cryopreservation was 38.3 years. The median time between the first cryopreservation and thaw was 4.2 years. The median numbers of oocytes and metaphase II oocytes (M2s) thawed per patient were 14 and 12, respectively. Overall survival of all thawed oocytes was 79%. Of all patients, 61% underwent ≥1 transfer. Among euploid (n = 262) and nonbiopsied (n = 158) transfers, the LB rates per transfer were 55% and 31%, respectively. The FLBR per patient was 39%. Age at cryopreservation and the number of M2s thawed were predictive of LB; the FLBR per patient was >50% for patients aged <38 years at cryopreservation or who thawed ≥20 M2s. A total of 173 patients (32%) have remaining inventory.

Conclusion(s)
Autologous oocyte thaw resulted in a 39% FLBR per patient, which is comparable with age-matched in vitro fertilisation outcomes. Studies with larger cohorts are necessary.

 

Fertility and Sterility article – Fifteen years of autologous oocyte thaw outcomes (Open access)

 

See more from MedicalBrief archives:

 

UK to increase storage limits for eggs, sperm and embryos to 55 years

 

UK fertility regulator: Freezing of eggs in 40s is ‘risky and not sensible’

 

Legal challenge to UK’s 10-year limit on egg freezing

 

Baby born through new egg freezing fertility treatment

 

‘Trading on hope’ — Fertility clinics exploit older women

 

 

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