The difference between donating and adopting embryos is purely legal. On the donation programme, the embryos are from couples who have given their express written consent for them to be donated to other people wishing to be parents. On the adoption programme, parents have not chosen a destination for their embryos and the medical centre decides. No special paperwork has to be completed for either of the processes and, on a medical level, both procedures are exactly the same.



At Institut Marquès the embryos assigned to the adoption programme are from young and healthy parents, where the mother is younger than 35. We also check the medical records of the parents and their other children born using IVF treatment.
The assigned embryos are from patients who have successfully undergone IVF treatment and do not want any more children. The vast majority are embryos from treatments carried out using donated eggs and/or sperm. The remaining embryos that have not been transferred are vitrified and preserved at the medical centre.
Parents may choose to donate their embryos to other patients or scientific research, or to have them destroyed. If no decision has been made after four years, the embryos are left in the care of the medical centre. In these cases, as long as they meet all the medical requirements, we put them up for adoption.



The Spanish Law on Assisted Reproduction (Law 14/2006), Chapter III, Article 11, states:
“The different possible uses found for cryopreserved pre-embryos and, where applicable, cryopreserved semen, oocytes and ovarian tissue, are:

1) Use by the mother herself or her spouse: the embryos are preserved, so that they can be implanted at a later date before the woman is no longer fertile and cannot receive embryos for medical reasons.
2) Donation to other women.
3) The end of their preservation: this requires the receiving woman to be no longer fertile, and this must be confirmed by a medical report issued by professionals outside the centre.
4) Donation to scientific research: patients must receive and sign a letter from the centre, specifying the research project the embryos are to be sent to, and they must waive the right to financial compensation resulting from this research.”
All details about the legislation on this issue can be found in the document outlining the Spanish Law on Assisted Reproduction.

The law states that embryos shall be considered abandoned and left in the care of the medical centre if parents fail to respond to two consultations regarding what they would like to do with them. In these cases, they will be put on the adoption programme at our centre.



Following IVF treatment, embryos that are not transferred to the womb are preserved through vitrification. Frozen embryos do not have to be transferred within a certain timeframe.
Embryos can be frozen at various stages of their development: from the day they are fertilised – they are still just a single cell at that point – up until five or six days later, at the blastocyst, stage, when they are made up of the 200 cells that will divide into all of the embryo’s structures.
During the first five to six days of life, embryos grow inside the external membrane of the oocyte and when the cells break out of this membrane (known as the hatching of the blastocyst), they leave and are immediately implanted in the inner lining of the womb. Therefore, this is the latest point at which they can be frozen. There is no limit to the amount of time embryos can survive in a frozen state.

The embryo vitrification process is initiated by immersing them in a cryoprotectant, in order to prevent the formation of ice crystals. The embryos are then drawn gently into white plastic sticks, or “straws”. These are placed in a freezer and quickly reach -196°C. The drastic change in temperature converts the embryos into a solid material similar to glass. The straws are then inserted into a container filled with liquid nitrogen.
Embryo vitrification is a laborious process requiring highly-trained hands, but it has significantly improved pregnancy rates, as the percentage of surviving embryos is approaching 100%.

In each of the liquid nitrogen containers, there is enough room for 10,000 embryos. They live in tanks with compartments, where siblings are put together in plastic pots and every family has its own colour. There can be one, two or three embryos in each straw, and these straws are deposited inside the pots. These sticks have a bar inside which is a specific colour and labelled with the family name. This way, each family has its own combination of colours and codes and, on our computers, we log where they are kept in the liquid nitrogen container for ease of identification.