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Blastocyst transfer

A frozen blastocyst transfer is an embryo transfer that involves transferring one or more embryos that are at a very advanced stage of development, called the blastocyst stage. This is usually done on the fifth day after follicular aspiration.

Embryo transfer of blastocysts

After the doctor has removed the eggs from an ovary (follicular aspiration), they are fertilised in the laboratory. This is done either by normal in vitro fertilisation (IVF) or by means of intracytoplasmic sperm injection (ICSI).

Immediately after fertilisation, an egg starts to divide and develop into an embryo. The stages of development are as follows:

  • Day 1: The pronuclear stage (fertilised egg)

  • Day 2: Two- to four-cell stage

  • Day 3: The eight-cell stage

  • Day 4: The morula stage

  • Day 5: The blastocyst stage

The doctor usually inserts one or more embryos in the woman’s uterus two to three days after egg retrieval. This process is referred to as embryo transfer.

The embryos can also develop in an incubator up to the fifth day, i.e. the blastocyst stage, thanks to improved cell culture media (blastocyst culture). If the doctor transfers such developed embryos into the woman’s uterus, this is referred to as blastocyst transfer.

Blastocyst transfer

What are the advantages of blastocyst transfer?

  • It is possible to identify embryos with development potential

Only 20 to 30 percent of the fertilised eggs develop into blastocysts at all. If an embryo reaches this stage, there is a higher chance of implantation.

  • The moment of blastocyst transfer is ideal

Just like with a blastocyst transfer, in a natural pregnancy, it takes around five days after fertilisation for the embryo to reach the uterine cavity, where it then implants. It is assumed that the lining of the uterus is particularly receptive on this day.

Legal background

In Germany, under the Embryo Protection Law, a maximum of only three fertilised eggs is allowed to mature to the blastocyst stage in an incubator. In addition, the German Embryo Protection Law prohibits the selection of embryos.

A decision on which of the fertilised eggs will be suitable for a blastocyst transfer is made during the first day after fertilisation, in the pronuclear stage. During this stage, the nuclei of the egg and sperm cells are not yet fused together. At this point, these cells are not yet embryos. Excess fertilised eggs in the pronuclear stage can be frozen (cryopreservation).

What are the success rates of blastocyst transfer?

The chances of getting pregnant after blastocyst transfer are very high. Compared to embryo transfer at an early development stage (day 2 or 3), the odds are increased by around seven percent (Source: DIR Jahrbuch – German IVF-Registry Annual 2014). In women up to the age of 30, the chance of success is between 45 and 50 percent, and for women aged 30-39 it is between 35 and 40 percent.

However,  blastocyst culture does not provide the same advantages for all women. Those with a low egg count and quality may indeed benefit from a day-3 transfer, in which the embryos are inserted in the mother’s uterus at an earlier stage. It, therefore, goes without saying that our reproductive medicine specialists will work together with you to determine the best transfer method for you as part of a personalised individual medical approach for the best possible chance of success.

We offer this service in:

  • Berlin


    10117 Berlin


  • Düsseldorf


    40219 Dusseldorf


  • Wiesbaden


    65189 Wiesbaden


  • Frankfurt


    60311 Frankfurt


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