IVF Birth Rate Higher When Gene Testing Isn't Added to Standard Observational Blastocyst Testing

By Gene Emery

November 29, 2021

NEW YORK (Reuters Health) - More-sophisticated genetic testing of embryos ready for implantation does not significantly increase the likelihood of a live birth among women who have at least three good-quality blastocysts. In fact, it may lower the success rate, according to a new Chinese study of 1,212 women.

The conclusion that conventional in vitro fertilization is not inferior to preimplantation genetic testing for aneuploidy (PGT-A) is based on the finding that live births eventually occurred in 81.8% of would-be mothers whose blastocysts received conventional morphologic screening versus 77.2% with both morphologic screening and next-generation sequencing (P<0.001).

The rate of clinical pregnancy loss was significantly higher with conventional screening than with PGT-A (12.6% vs. 8.7%), but the study only enrolled women with a good prognosis for live birth and they had healthy blastocysts to use as a backup.

"Although the frequency of pregnancy loss among clinical pregnancies appeared to be lower in the PGT-A group, this differential did not translate into a higher cumulative live-birth rate or shorter mean time until a live birth," Dr. Zi-Jiang Chen of Shandong University, in Jinan, and colleagues write in The New England Journal of Medicine.

The findings suggest "that the application of PGT-A in clinical practice should be cautious," Dr. Chen told Reuters Health in an email. "PGT-A is an expensive and invasive technology. Therefore, not doing PGT-A can help save money and avoid the potential harm from biopsy for patients who would not benefit from it."

Other studies have suggested that PGT-A might offer a better chance of a live birth, especially among older women.

"These studies focused on pregnancy outcomes after the first embryo transfer, rather than the cumulative live-birth rate for a given oocyte retrieval cycle," the researchers note. "However, the cumulative live-birth rate is considered to be the most important patient-centered outcome in evaluating the success of an IVF program."

"We hope our findings can impact genetic counseling practice in clinics and help doctors make decisions regarding the use of PGT-A," said Dr. Chen.

Another factor is cost. "In China, the procedure of biopsy and testing costs an additional $550 per embryo," the researcher said. "For women who had a good prognosis for a live birth, not doing PGT-A can help them save that money."

The findings do not apply to women who do not have a good prognosis due to, for example, recurrent miscarriage or recurrent implantation failure.

The randomized comparison was done at 14 academic fertility centers in women ranging in age from 20 to 37. Intracytoplasmic sperm injection was used for fertilization.

The researchers found that, on average, 1.2 embryos in the PGT-A group were transferred to produce a live birth compared with 1.3 embryos in the conventional IVF group.

While 119 of the 606 women (19.6%) in the PGT-A group underwent a second embryo-transfer cycle to get a live birth, 192 of 606 women (31.7%) in the conventional IVF group needed a second embryo.

The number of women who needed a third cycle in each group was five and 49, respectively.

There was no difference in the rates of moderate or severe ovarian hyperstimulation syndrome, ectopic pregnancy, obstetrical or perinatal complications, or congenital anomalies between the two groups.

"There is an urgent need for doctors to define the application scope of PGT-A and avoid its overutilization in clinical practice," said Dr. Chen. "Thus, we intend to further investigate the clinical effectiveness of PGT-A in poor-prognosis women, such as with recurrent implantation failure, recurrent pregnancy loss, etc."

SOURCE: https://bit.ly/3qV5zEa The New England Journal of Medicine, online November 24, 2021.

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