What are blastocy​sts and what is their importance?

With the increasing popularity of blastocyst assisted reproduction treatment, the specialist fertility clinic ProcreaTec explain all you need to know and whether this is a potential infertility treatment for you.

What is a blastocyst?

A blastocyst is an embryo that has developed for five to six days after fertilization. It is made up of two types of cells: the outermost layer, the trophoblast, which will later develop into the placenta, and the inner cell mass, which will become the baby.

Blastocyst transfer is potentially appropriate for everyone who obtains a few good quality embryos by day 3. One of the principal advantages of transferring at blastocyst stage for women under 38 and women using donor eggs is the ability to transfer a single embryo and still have the same chance of pregnancy as transferring two on day 3, with next to no risk of having twins.

Advantages of blastocyst transfer

There are four important reasons that illustrate the advantages of blastocyst transfer:

  1. In a spontaneous pregnancy, fertilization occurs in the Fallopian tubes and the embryo develops while rolling down the tubes towards the uterus. Five days after fertilization takes place- when the embryo has become a blastocyst- it reaches the uterine cavity. One to five days later, implantation occurs. When a blastocyst from IVF treatment is transferred and implants, it closely mirrors the natural process of implantation i.e. reaching the uterus on Day+5 and implanting one to five days later.
  2. A laboratory embryo that survives until Day+5 of development is a high quality embryo with implantation potential. Transferring the embryo when it is at the blastocyst stage notably increases the chances of pregnancy.
  3. When going to Day+5 a natural selection of embryos takes place. This enables the embryologist to select the best quality embryo available for transfer in a more effective way.
  4. And lastly, when freezing embryos in the blastocyst stage, only embryos with high implantation potential are stored. The implantation rate of these embryos in a frozen thaw cycle equals the rate of fresh blastocyst transfer.

What are the disadvantages?

The goal of Assisted Reproduction is to help a woman have one healthy take-home baby. When transferring two blastocysts, the twin pregnancy rate is much higher and owing to this fact, single blastocyst transfer should be considered.

About ProcreaTec

Since its establishment, ProcreaTec has been a firm believer in transferring blastocysts on day five. Due to the optimal conditions at ProcreaTec’s lab, our pregnancy rates at blastocyst stage are comparable to the best IVF centers worldwide.

This article was submitted by Procreatec, an internationally recognised fertility center in Madrid, Spain.


Author profile

ProcreaTec is an international fertility center in Madrid, Spain. Offering a high quality, personal service from a small but highly experienced team comprising fertility specialists, embryologists, a urologist, a psychologist and a team of friendly nurses and customer care staff, they provide a wide range of fertility treatments, from basic assistance to the most modern and sophisticated techniques.

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