Assisted fertilization and probability of success, how does it work and why does the embryo fail to implant in one out of two cases? – time.news

2023-06-30 08:29:48

by Elena Meli

A large study has now identified the reasons why this happens: mother’s age, obesity and repeated bankruptcies are the most frequent causes

It happens to many couples who start an assisted fertilization process: the procedures are successful, a healthy embryo is obtained to be implanted but then something goes wrong and the pregnancy does not proceed. The negative test, the burning disappointment. Why, in one out of two cases, even euploid, or chromosomally normal, embryos are not implanted? Today there is finally some answer thanks to research coordinated by Italian experts, presented in Copenhagen at the last congress of the European Society of Human Reproduction and Embryology (ESHRE).

Black box

The researchers analyzed over 400 scientific papers by opening what is called the black box of medically assisted fertilization, looking for the reasons for the failures after a transfer of good embryos. Dozens of characteristics were evaluated which were supposed to have an influence on the implantation of the embryo, from specificities of the embryo itself to maternal or paternal elements, up to laboratory or clinical factors. The results indicate that some parameters seem really relevant, as explained by the head of the study Danilo Cimadomo, head of research and development of the Genera group and coordinator of the scientific committee of the Italian Society of Embryology, Reproduction and Research (SIERR): Among the characteristics with a greater maternal age over 38, maternal obesity, repeated failures in previous attempts influence the failed implantation of the embryo. Nothing significant emerged from the paternal side, for example an influence from the DNA fragmentation of the sperm; It is possible that these elements count more when the female partner is young, while after the age of 38 the maternal characteristics weigh above all.

Procedure

As for pre-implantation diagnosis, it emerged that it is better to freeze the embryo while awaiting the outcome rather than waiting to implant it “fresh”, continues Cimadomo. It may seem counterintuitive, in reality the embryo, by continuing to grow, could become desynchronized” with the ideal moment for the transfer. A less invasive biopsy technique, which takes the embryo from the incubator on day 3, was also associated with better outcomes; many, therefore, are factors on which we can intervene and in any case we are dealing with data that can help couples make better choices. It must also be said that failure is part of the process, trying again is important, Cimadomo points out. In fact, today we are talking about a “multicycle” approach, because we know that from the first to the third cycle the chances of success increase. from the third to the sixth it seems that the plateau of pregnancy possibilities is reached, but it is important that each couple makes the most of their potential to have a child, according to the path that best suits their characteristics.

June 30, 2023 (change June 30, 2023 | 08:29)

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