Embryo donation

Embryo donors are women or couples who have undergone assisted reproduction treatment (in vitro fertilisation, egg donation) and who, in most cases, have successfully had children. Once their reproductive project is complete, they decide to dispense with the frozen embryos, taking advantage of the possibility offered by current legislation to donate them for reproductive purposes.

Embryo donors, women or couples who have undergone assisted reproduction treatment, have undergone the tests required by current legislation. As general characteristics, they are healthy individuals who have tested negative for infectious diseases transmissible by law, with women under 35 and men under 50.

Embryo reception is indicated when both partners have reproductive problems. The most common indications are:

• Premature ovarian failure, whether spontaneous or caused by surgery, chemotherapy, or radiotherapy
• Serious genetic diseases with a high risk of transmission that cannot be diagnosed early on.
• Previous failure of assisted reproduction techniques
• Repeated embryo implantation failure

The timing depends on the circumstances of each woman or couple. In some cases, embryo transfer may be the first and only option available within assisted reproduction techniques, while in others it is considered a last resort if pregnancy has not been achieved using other assisted reproduction techniques.

Once the decision has been made, the medical team selects the donated embryos, seeking the greatest possible phenotypic and immunological similarity with the recipient woman or couple.

From this point onwards, the process is the same as for a frozen embryo transfer: the recipient woman undergoes hormone treatment to prepare her uterus to receive the embryos, and when it is in optimal condition, the assigned embryos are thawed. After thawing, embryo survival and viability are assessed, and the transfer is performed on the scheduled day.

If none of the thawed embryos were viable, a new group of embryos would be assigned to ensure that the transfer could be carried out.

Our unit has an embryo survival rate of between 80% (zygote stage) and 95% (8-cell stage).

The procedure is relatively short, as it takes about two weeks of hormone treatment to get the uterus in optimal condition for embryo transfer.

It is as safe a procedure as any other in assisted reproduction. Maximum safety can be guaranteed provided that it is carried out under the conditions established by law.

The recipient woman receives hormone treatment to prepare the uterus for embryo transfer, which involves placing the embryos in the uterine cavity through the vagina. The transfer is the final stage in assisted reproduction treatment, so the most important thing is to follow your doctor's instructions regarding both medication and physical activity.

The transfer procedure itself is very short, taking between ten and twenty minutes from the time the patient enters the operating theatre until she leaves.

Embryos donated by a woman or couple retain the same biological characteristics they had before being donated; the only change is legal in nature. This means that, technically, donated embryos are the same as any other embryo and can therefore be genetically analysed.

In any case, genetic analysis of these embryos is not common, as most of them come from the same series of embryos that have resulted in pregnancy and the birth of healthy children in the donor couples, and this circumstance counteracts the potential risk of embryos coming from couples with fertility problems. Furthermore, recent studies with frozen embryos indicate that freezing has no adverse effects on the rate of abnormalities in newborns.

Own embryos are defined as embryos belonging to a couple. These embryos may originate from the gametes (eggs and sperm) of the parent couple or they may come from donor gametes.

Since embryo reception is indicated when both partners have reproductive problems, the option of generating their own embryos would involve undergoing a cycle with donor eggs and fertilising them with donor sperm.

The main difference between the option of an egg donation cycle with donor sperm and that of receiving donated embryos is the number of embryos available. In egg donation with donor sperm, all embryos generated in that cycle belong to the recipient couple and, furthermore, the transfer can be carried out fresh; whereas in embryo reception, the number of embryos available is usually lower, from 3 to 5 embryos, as these are frozen embryos left over from assisted reproduction treatment.

The clinical pregnancy rate is very remarkable. This positive result can be explained by the fact that this is a selected population of embryos, most of which belong to the same series of embryos that have previously resulted in pregnancy and birth in the donor couples.

In our unit, the clinical pregnancy rate per transfer is 39.2% with an average of 2.1 embryos per transfer, and approximately half of the recipient women (52.2%) achieve pregnancy with an average of 1.3 transfers per patient.