How Long Can Embryos Be Stored and Used

 

On many occasions, couples that are going through in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatment choose to store the leftover embryos instead of discarding them. The embryos are frozen for their future use. Intended parents can use those embryos in case their first attempt of pregnancy is not successful. They can also use the stored embryos if they plan for another child.

Couples undergoing certain medical treatments that might damage their fertility opt for embryo freezing. People receiving radiotherapy or chemotherapy have greater chances of getting their fertility spoilt eventually. Hence, if they want babies with their own embryos and are already anticipating a progressive condition that can affect their fertility, they can go for embryo freezing.

Freezing and Storing Embryos

Embryo freezing is not a new thing in IVF. It started back in 1984 when the first human embryo was frozen for future use. Countless embryos have been frozen since then and thousands of babies are born from those frozen embryos. Embryo freezing, in fact, has become a very routine part of IVF treatments. More than 60% of patients choose to save some embryos in storage. Such storage is done after considering all the possible results of the IVF procedure. In case the couple needs to go for another attempt, they can already have an embryo of their own.

Freezing the best quality embryos after an IVF procedure permits the transfer of lesser embryos in the next fresh IVF cycle. Thus, they ensure lesser multiple births. There are lesser chances of triplets or more due to this. This procedure creates a back-up for the couples- in case the initial fresh embryo transfer did not develop into a pregnancy, they can initiate another IVF cycle at a much lower cost and with minimal medications.

Transfer of frozen embryos has made it possible for many couples to achieve more than one pregnancy from an individual cycle of ovarian stimulation. The extra embryos can be stored for future use at any stage of development in the IVF procedure. Fertilised eggs can be successfully frozen within 1 day of the egg retrieval procedure. However, the embryos are generally allowed to develop for a few days before being frozen. Thus, the development of the embryo can be tracked and its efficiency to create a baby later on can be well anticipated.

Embryos are frozen at definite temperatures. More than 90% of the embryos are able to survive this freezing process and gives a good rate of successful pregnancies. Frozen/thawed embryos are equally effective in initiating a pregnancy like the fresh transferred ones.

Freezing Embryos During IVF

Normally there are 9 to 10 eggs collected in an IVF cycle. 60% of these eggs get fertilised with the healthy sperm. Nonetheless, there are limited numbers of embryos that can be transferred in order to reduce the risk of multiple births. Hence, cryopreservation or spare embryo freezing has become a commonly accepted procedure for the couples to avoid multiple births and to ensure future attempts.

There is a lot of pressure on the IVF clinics from the couples to ensure no multiple births. This is the reason single embryos are transferred and the remaining are frozen for later treatments.

There is no clear evidence that embryo freezing can be harmful for later use. However, the following points will justify the logic behind this procedure:

1. Women at a later age cannot invest time on another IVF procedure if their first attempt fails. In such cases, women usually after the age of 35 choose to store their spare embryos, so that they can use them in their next attempts of IVF cycle if required.

2. Women undergoing cancer treatment save their embryos for later use as their eggs get affected in the ovaries during her radiation or chemotherapy treatment.

3. Women suffering from malignant diseases like leukaemia have been successful in conceiving with the stored embryos collected before adverse medications that might make them sterile has been administered.

4. On occasion, women become ill during their IVF procedures. This happens in rare cases due to drug reactions that cause hyperstimulation. In such cases, embryo transfer is delayed through freezing storages, so that they are able to carry on with the procedure once they have recovered.

5. Frozen embryos are donated by the genetic parents to other infertile couples as well. Infertile couples going through failed attempts of pregnancy can successfully gain pregnancy through donated embryos. It saves them from delay and frustration in achieving a successful pregnancy.

6. The frozen embryos are also used for research and studies in the field of IVF.

Longevity of Frozen Embryos

A 26-year-old woman Tina Gibson became known after she gave birth to her child by using a 24 years old frozen embryo. She gave birth to her daughter Emma after achieving pregnancy through in vitro fertilization (IVF). Her husband Benjamin was suffering from cystic fibrosis and, hence, the couple was facing infertility for years. They finally gained pregnancy through IVF treatment and successfully gave birth to a healthy child by using embryo that is almost two and a half decade old. This proves that embryos can be stored for a long period once properly frozen. The quality of the embryo does not deteriorate with time. This birth is actually a record in the IVF treatment. It has opened up the eyes of many couples who were previously in doubt about the use of frozen embryos. There is actually no storage period limitation for embryos. Since they are medically cryopreserved, they remain in the same state for decades.

The survival rate of these frozen embryos are 98%. In some cases, the embryos are found to have dead cells that are identified after they are thawed. Once the vitrified embryos are warmed, they work equally effective like any of the fresh embryos. They have the same chances of developing into a pregnancy like the fresh ones. In fact, use of frozen eggs has decreased the cost involved in the IVF procedure for infertile couples. Many of the infertile couples choose to go for embryo donation to save time, money and energy. They get quality embryos well within their budget in a specific time period.

Success Rates of IVF with Frozen Embryos

The first baby was born from a frozen embryo in the year 1986. Cryopreservation has been in use in IVF procedure from 80’s and is still being used. The success rate of IVF procedure with the usage of frozen embryos is about two-thirds of the success rate with fresh embryos. There is no specific number associated with the rate of success with cryopreserved embryos, but this procedure has gained popularity due to its lower cost.

Children born out of cryopreserved embryos are as normal as the ones born from fresh embryos. There is even no abnormality noticed in the embryos that lose some cells during thawing. Freezing or cryopreservation of embryos does not cause any genetic abnormalities in the child.