Modern IVF treatments can dramatically reduce twin and triplet pregnancies while achieving significantly higher success rates than traditional approaches, according to new research presented today at the 42nd European Society of Human Reproduction and Embryology (ESHRE).
In one of the largest IVF studies of its kind, researchers analyzed the results of 18,396 women who underwent their first IVF cycle between January 2012 and December 2021 and were followed up until December 2023 at seven Australian fertility clinics.
The study found that modern IVF clinical practice achieves a cumulative live birth rate of 68.2% over three treatment cycles, while using single embryo transfer in 95.3% of embryo transfers and maintaining multiple birth rates at only 2.9%.
This discovery represents a significant improvement over previous IVF outcomes. Early studies conducted before the widespread adoption of modern IVF testing techniques reported a three-cycle cumulative live birth rate of approximately 53-59%, with multiple pregnancy rates often exceeding 20%. The researchers say the improved outcomes likely reflect advances such as blastocyst culture, embryo vitrification, freeze-all strategies, and optimized frozen embryo transfer protocols, which are now widely used in modern IVF treatments.
The researchers examined cumulative live birth rates over up to three IVF cycles using modern clinical protocols, including expanded blastocyst culture (days 5-6 of embryonic development), embryo vitrification (rapid freezing), and selective whole-freezing approaches when appropriate. Women using donor eggs, frozen eggs, or certain genetic testing routes were excluded from the analysis. For all women, the cumulative live birth rate over three treatment cycles reached 58.7% using intention-to-treat analysis and 68.2% using optimal per-protocol analysis.
Success rates vary greatly depending on age. Women under 35 years achieved an optimal cumulative fertility rate of 84.5%, compared with 74.4% for women 35-37, 57.7% for women 38-40, and 30.1% for women 41-42.
Lead author Dr. Dean Morbeck said the study results reflected 10 years of gradual progress in IVF laboratories and clinical practice.
The biggest change is that blastocyst culture has gone from being the exception to being the default. This change has driven improvements across the IVF lab, including lower oxygen conditions, specialized incubators, and minimal disruption to embryos during culture. ”
Vitrification also significantly increased the efficiency of blastocyst culture, dramatically increasing embryo survival after freezing and warming, and making frozen embryo transfer results comparable to fresh transfers. These advances have enabled approaches such as freeze-all therapy, in which embryos are transferred one at a time later rather than during the first stimulation cycle. ”
Dr. Dean Morbeck, lead author
The study compared results before and after laboratory improvements introduced since 2016, such as single-step media and time-lapse embryo culture, and also examined changes over time. Between 2012-2015 and 2017-2021, the proportion of zygotes that developed into usable blastocysts increased from 48.3% to 57.6%, and single embryo transfers increased from 92.8% to 97.3%. Over the same period, multiple birth rates fell from 3.2% to 2.7%.
Dr. Morbeck said the findings challenge the long-held assumption that multiple embryos need to be transferred to maximize IVF success.
“For many years, transferring two embryos increased the chance of pregnancy after one transfer, but in many cases the twin pregnancy rate approached 30%,” he explained. “Our data show that this trade-off has largely disappeared.”
“In more than 18,000 women, we used single embryo transfer in 95% of cases and achieved a high cumulative birth rate while keeping the twin birth rate below 3%. Our concerted efforts to reduce twin pregnancies did not sacrifice our patients’ chances of bringing their babies home; it coincided with an increase in that chance.”
The findings also suggest that strong IVF results can be achieved without the routine use of preimplantation genetic testing for aneuploidy (PGT-A), a test used to screen embryos for chromosomal abnormalities before implantation, in all patients.
PGT-A was used in 1 or more treatment cycles in 25% of women in the study. However, Dr. Morbeck pointed out that most live births were performed without regular genetic testing of the embryos.
“PGT-A plays an important role in some patients, especially women who give birth at an older age or who have infertility,” he said. “However, our findings should reassure many patients that strong IVF outcomes are achievable without necessarily requiring routine genetic testing.”
Dr. Maubeck discussed the implications of this result and said it supports continued efforts to increase access to single embryo transfer internationally. “The future of IVF is to continue to improve the success rate of each embryo transfer, while maintaining the safety improvements we have achieved to date,” he said.
Reflecting on the importance of the research, Professor Bort Kovačić, ESHRE’s incoming chair, said: “Improvements in IVF are typically driven by steady, incremental progress, rather than dramatic advances. This research aims to optimize laboratory practices, adhere to evidence-based guidelines and “We show that by adopting a relatively conservative treatment approach, we can reduce multiple births while gradually increasing cumulative birth rates. These two results are of paramount importance for patients seeking a safe and cost-effective way to raise their children in a single birth.” stimulation cycle. ”
The research summary is today. human reproductionone of the world’s leading reproductive medicine journals.
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European Society of Human Reproduction and Embryology
