Blastocyst Transfer

Thousands of couples every year opt to go through IVF fertility treatment in order to increase their chances of conception. If you and your partner are considering an IVF procedure, then you may have heard of many successful procedures performed using blastocyst transfer. Blastocyst transfer is becoming more and more popular in North American fertility clinics, and may help you to increase your chances of IVF success.

What is Blastocyst Transfer?

Blastocyst transfer is a type of embryo transfer procedure used during IVF. This type of transfer was first performed 30 years ago and is now being used in an increasing number of fertility clinics. During this type of transfer, a blastocyst embryo is placed inside of your uterus where it will hopefully implant and develop into a fetus. It is now becoming a popular alternative to Day 3 embryo transfer.

What is a Blastocyst?
A blastocyst is formed when an embryo reaches the five to seven-day development stage. At this point in development, the embryo has between 60 and 100 cells distributed in two areas: an outer embryo lining (which will later form the placenta), and an inner mass (which will later become the fetus). During a natural cycle, the embryo develops into the blastocyst stage as it is leaving the fallopian tubes and entering the uterus. An embryo needs to have entered into the blastocyst stage once it arrives in the uterus to ensure proper implantation.

How Many Embryos are Transferred?
Should you decide on a blastocyst transfer, it is likely that only one or two of your embryos will be transferred into your uterus. Fewer embryos are required for this type of transfer because blastocyst embryos are more likely to implant and develop than Day 3 embryos. Typically, between two and four embryos need to be transferred during a day 3 transfer procedure.

Why is Blastocyst Transfer Becoming So Popular?

Blastocyst transfer is becoming extremely popular amongst reproductive endocrinologists and infertile couples. A blastocyst transter is associated with a number of advantages over the typical Day 3 transfer procedure.

A Natural Option
Blastocyst transfer is considered a more "natural" type of transfer than the Day 3 transfer procedure. This is because the blastocyst embryo is implanted into the uterus at almost the same time that it would have entered the uterus should the pregnancy have been a natural one. Alternatively, during Day 3 transfers, embryos are placed inside the uterus at a time when they should normally still be in the fallopian tubes. It is believed that by waiting to transfer a blastocyst embryo, a woman may be more likely to achieve a successful pregnancy.

Higher Success Rates
Blastocyst embryo transfers have also been associated with better IVF success rates. By allowing embryos to culture for a longer period of time, embryologists are better able to choose healthy embryos to transfer into your uterus.

Not all embryos are strong enough to reach the blastocyst stage of development; in fact, approximately 50% of all embryos die soon after the third day of development. By holding transfer off until the blastocyst stage, your embryologist will be better able to ensure that your embryos are healthy and capable of further development. Blastocyst transfer is associated with almost a 50% success rate, compared to the usual 35%.

Fewer Embryos Required
Many couples opt for blastocyst transfer because fewer embryos need to be transferred. This helps to significantly decrease the chances that you should develop a multiple pregnancy. Twin, triplet, and higher-order pregnancies can be very dangerous for both the babies and the mother. If you experience a multiple pregnancy you are at increased risk for miscarriage, stillbirth, and having low birth weight babies. Many couples opt to avoid these dangers by undergoing the blastocyst transfer procedure.

Should You Get a Blastocyst Transfer?

Before you and your partner decide on a blastocyst transfer, it is important to consider whether or not you are suited for the procedure. Blastocyst transfer does have its disadvantages and may not be appropriate for all couples.

Who Gets a Blastocyst Transfer?
Some couples are more suited to blastocyst transfer than others. You may be a good candidate for this type of transfer if:

• you have not had success with previous Day 3 transfers.
• you have a relatively small number of embryos available for transfer.
• you need to avoid having a multiple pregnancy for health reasons.

Disadvantages of Blastocyst Transfer
Blastocyst transfer does have a few disadvantages associated with it:

• Difficulty: Blastocyst culture is very difficult to do and requires a fully-equipped laboratory and intensive management. In order to survive the culture process, embryos need to be kept at specific temperatures and exposed to just the right culture medium. Some fertility clinics have not yet perfected this culture process and, as a result, have lower success rates.
• Loss of Embryos: If you choose to have a blastocyst transfer, expect to lose quite a few of your embryos. On average, up to 50% of embryos die before the blastocyst stage, but some couples lose more than half of their embryos.
• Freezing Difficulties: Many couples opt to pursue cryopreservation of any leftover embryos so that they can use them for fertility procedures in the future. Unfortunately, blastocysts do not survive the freezing process as well as Day 3 embryos do, so this may not be a option for you.