A recent study from China suggests that women with a low chance of a successful pregnancy through in vitro fertilization (IVF) may have better outcomes with fresh embryo transfer compared to using frozen embryos. The research, published in The BMJ, challenges the common practice of freezing all embryos before transfer, a method known as the “freeze-all” strategy.
IVF has revolutionized infertility treatment, and the freeze-all strategy has become a standard procedure to prevent overstimulation of the ovaries during egg retrieval. Most previous studies on the freeze-all strategy have focused on women with a high likelihood of IVF success, showing similar live birth rates for both fresh and frozen embryo transfers. However, little was known about the effectiveness of this strategy for women with a lower chance of success, such as those of advanced age or with poor egg quality.
To fill this gap, the researchers conducted a trial involving 838 women aged 33 to 34 with a low IVF prognosis. The women were randomly assigned to either a fresh or frozen embryo transfer group at nine fertility centers in China. The researchers then monitored live birth rates after the first embryo transfer until April 2024.
The results showed that 40% of women in the fresh embryo transfer group had a live birth, compared to 32% in the frozen embryo transfer group. Additionally, the fresh embryo group had higher pregnancy rates (47% vs. 39%) and higher cumulative live birth rates over the course of the year (51% vs. 44%).
The study found no significant differences in birth weight, pregnancy complications, or health risks for newborns between the two groups. However, the researchers noted that differences in the number and stage of embryos transferred may have contributed to the higher success rate in the fresh embryo group.
Despite these limitations, the study suggests that fresh embryo transfer may offer better live birth rates for women with low IVF success chances. The researchers recommend further studies to determine the optimal number and stage of embryos for fresh transfers in these patients.
In a linked editorial, experts from the Netherlands highlighted potential biases that could affect the study’s outcomes. They also raised concerns about the broader implications of freezing embryos across multiple IVF cycles before the first transfer, noting that any potential benefits of this practice must outweigh its drawbacks.
The trial provides valuable insights for women facing IVF challenges, but ongoing research is needed to optimize treatment strategies for this patient group.
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