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When was the first egg frozen?

Frozen eggs
The cryopreservation of oocytes and embryos by means of vitrification is a relatively novel technique with a long history of research and development behind it. From the first methods used to preserve fertility to those available nowadays, great advancements have been made with the aim of improving oocyte survival rates.

The first pregnancy achieved from a frozen egg

Nowadays, vitrification is the procedure used to cryopreserve eggs and embryos in IVF treatments. It’s taken several decades to perfect this technique and find an effective way to preserve eggs or embryos without damaging them.

The first pregnancy achieved from a frozen egg was reported by Chen in 1986 (Chen, 1986). However, due to the low success rates obtained, it wasn’t until 10 years later that oocyte cryopreservation was resumed. This is due to the fact that the oocyte, as the largest cell in the body, has a high-water content, and low temperatures cause intracellular ice crystals to form, thus damaging the cell.

For this reason, it was more common to use cryopreserved embryos. The main advantage was that, although some cells could be lost during the thawing process, others survived, and the embryo was able to develop.

However, one of the drawbacks with using frozen embryos was that it was not always the most practical option for the patient. Certain situations could lead to potential complications, as in the following cases:

  • If the woman didn’t have a partner at the time of deciding to preserve her fertility, and didn’t want to use donor sperm, it wasn’t possible to produce an embryo to freeze.
  • If the woman was single when she made the decision to use donor sperm to create the embryo, but in a relationship at the time of the embryo transfer, the baby would not be biologically related to the future father. This was a possible cause of issues between the couple, resulting in the patient no longer wanting the embryo.
  • If the woman was no longer in a relationship with the partner whose sperm was used to create the embryo, it wasn’t possible to perform the transfer.

The development of vitrification methods brought improved procedures that consisted of dehydrating the oocytes so that there was no water to form ice crystals, and adding cryoprotectants to the media to improve survival rates. However, the concentration of cryoprotectants present in the vitrification solution had to be strictly monitored, as high levels had a toxic effect on the oocytes.

Once adequate oocyte survival had been achieved, the world of fertility preservation was revolutionised. The first reported birth from a vitrified egg was in 1999 (Kuwayama and Kato, 2000). By 2009 (Chian et al., 2009), more than nine hundred babies had been born from cryopreserved oocytes.

Since its introduction, vitrification is the only method used due to its high success rates, regardless of the reason why each woman wishes to freeze her eggs. Thanks to this procedure, oocyte survival rates have increased to almost one hundred percent, allowing egg banks such as Ovobank to exist today.

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