Fresh embryo transfer can improve IVF success for women with a poor prognosis

Fresh embryo transfer can improve IVF success for women with a poor prognosis

Fresh embryo transfer may be a better option than using frozen embryos for women with a low likelihood of having a healthy baby through vitro fertilization (IVF).The BMJToday.

The researchers say their results do not support the routine use of the freeze-all strategy in women with low prognosis of IVF treatment success due to older age, low quantity or quality of eggs, or certain underlying conditions.

IVF has revolutionized the treatment of infertility and the strategy of freezing all suitable embryos before transfer (freeze-all strategy) is now a routine part of treatment to prevent the ovaries from being overstimulated with fertility drugs to obtain fresh eggs.

Most studies examining the freeze-all strategy focused on women with a good prognosis of IVF treatment success, showing similar cumulative live birth rates between fresh and frozen embryo transfer. However, it is unclear whether women with poor prognosis also benefit from this strategy.

To address this evidence gap, researchers set out to compare live birth rates after fresh and frozen embryo transfer in 838 women aged 33 to 34 years with a low prognosis for IVF treatment success at nine fertility centers in China.

Between December 2021 and May 2023, participants were randomly assigned to two groups and underwent either frozen or fresh embryo transfer. The live birth rate after the first transmission was then monitored until April 2024.

A total of 132 (32%) of 419 women in the frozen embryo transfer group had a live birth, compared to 168 (40%) of 419 in the new embryo transfer group.

The frozen embryo group also had a lower pregnancy rate than the fresh embryo group – 39% (164 of 419) V 47% (197 of 419) – and a lower cumulative live birth rate after further embryo transfers within one year of randomization – 44% (185 of 419) V 51% (215 of 419).

No differences in birth weight, obstetric complications, or neonatal morbidity risks were observed between the two groups.

The researchers acknowledge some limitations, including differences in the number and stage of embryos transferred, which may partially contribute to the difference in live birth rates between groups.

However, they say the results add to previous studies of women with a good or normal prognosis and capture the range of benefits and risks of the freeze-all strategy compared to the fresh embryo transfer strategy.

They conclude: “Fresh embryo transfer may be a better choice for women with a poor prognosis for IVF compared to frozen embryo transfer.”

And they say further studies are needed “to investigate the optimal number and stage of embryos for new transfer in women with poor prognosis for IVF to have a singleton pregnancy.”

This study offers valuable insight to women with a poor prognosis in IVF, but concerns about potential bias that may influence the results, researchers from the Netherlands write in a linked editorial.

They also point to broader implications, particularly for centers offering advanced IVF treatments that include freezing embryos from multiple IVF cycles before a first transfer, saying: "Any potential benefits must outweigh any disadvantages."

“Proper evaluation of the effectiveness of these techniques is essential for improving outcomes in this challenging patient population,” they conclude.

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