Transferring embryos in in a delayed way does not affect the success of reproductive treatments
A group of researchers from various hospitals and assisted reproduction centers, public and private, in Denmark, Sweden and Spain, including Dr Nikolaos Polyzos, head of the Reproductive Medicine Service of Dexeus Mujer, has carried out an extensive study to check whether the transfer of previously vitrified embryos can offer a pregnancy rate comparable to cycles performed in fresh. There was some precedent work in China and Vietnam or minority work in the United States, but to date, no large multicenter study on this topic has been conducted in Europe.
A total of 460 women between 18 and 39 years old participated in the study, with regular menstrual cycles who were included during the beginning of their first, second or third cycle of in vitro fertilization or ICSI (intracytoplasmic sperm microinjection). The patients were divided into two groups: in the first group, it was decided to vitrify all the embryos obtained after ovarian stimulation and fertilization in the laboratory, and one that was previously thawed was transferred to them; In the second group, a conventional IVF process was followed, and a single embryo was also transferred but in a fresh cycle. The results when comparing both groups showed that the pregnancy rate did not offer significant differences, being 27.8% in the group in which vitrification had been chosen vs 29.6% in the patients who had performed the cycle fresh. Likewise, the rate of children who were born later was practically the same: 27.4% for the group that opted for vitrification, and 28.7% registered in the group that performed the fresh cycle. Furthermore, the authors conclude that there are no significant differences in the number of children finally born in both groups or in the appearance of complications during pregnancy, childbirth or neonatal.
The results of this work are decisive in the current context of the COVID-19 pandemic, since they show that the strategy of vitrifying biological material in the face of confinement or interruption of treatment to which some patients have been forced, is not going to the detriment of the success of reproductive treatments that use this material and carry out delayed embryo transfer.