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“Single Embryo Transfer” in IVF – Facts and background information

Part 5 of the topic-series »Fertility treatment procedure«

[← article overview of the topic-series »Fertility treatment procedure«]

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“Does the transfer of two embryos increase my chances of becoming pregnant?”

This question is frequently asked by couples who want to learn more about the envisaged fertility treatment – for instance when they join us at our monthly information evenings in Salzburg. (→ for details, please click here)

My answer seems quite clear: “only marginally (5-7%)”

Why is that?

Course of an IVF treatment

In IVF treatment, the process of fertilization which involves the union of oocytes and sperm occurs outside the female body in the laboratory (In Vitro Fertilization – IVF). The fertilized oocytes are incubated in a special culture medium and placed in an incubator to develop into embryos. Once the embryos have reached a certain stage of development (blastocyst), they are placed into the woman’s uterus (embryo transfer). Ideally, this is done on the fifth day following fertilization which, in “natural” conception, corresponds to the time by which the embryo will have migrated from the Fallopian tube into the womb to implant itself into the endometrium (→ for more details on all steps of the treatment, please click here).

Trend towards “Single Embryo Transfer”

At our IVF Centers, treatment is focused on the so-called “Single Embryo Transfer”. This means that perfect conditions must be created in the run-up to the treatment, thus making it possible to transfer only one embryo with the highest implantation potential. Hence, a great deal of experience is required, as well as optimized stimulation protocols, individually adjusted medication and the use of cutting-edge laboratory techniques.

A “Single Embryo Transfer” enables us to reduce the risk of multiple pregnancies to below 5%. The transfer of 2 embryos, by contrast, increases the risk of multiple gestation pregnancy to 20–25% (triplets 2-3%). This risk is in contrast to an insignificant improvement in pregnancy rate, rising by just a marginal 5-7%.

For the purpose of comparison, we will look at the following example: In women under 32 years of age, pregnancy tests come back positive in 70% of the cases after transferring only one embryo (following blastocyst selection) to the woman’s uterus after optimal endometrial preparation.

Depending on the couple’s individual situation, we believe that the number of embryos to be transferred should not exceed two.

The aim is as follows: “One treatment with the transfer of one embryo results in a successful singleton pregnancy with the birth of one healthy child”.

» Success rate – What couples need to bear in mind

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