Regardless of whether after IVF or IVF/ICSI, as well as in what is known as the “frozen embryo cycle”, embryos can be cultivated for 2 to 3 days, or up to day 5. This is possible even in Germany, with its strict Embryo Protection Act. It is performed with great success by a few centres. Until quite recently in Germany cells had to be selected at the stage of the fertilized egg before it´s development potential could be accurately be determined.. In order to reach an acceptable pregnancy rate more embryos had to be transferred (see the IVF Register www.deutsches-ivf-register.de).
Modern embryo culture allows cultivating embryos until day 5 or 6. An embryo that reaches the so called blastocyst stage on day 5 is known to have a high potential for implantation. We call it a “Top-Quality-Embryo”!
Only 25 – 50 % of the day-2-embryos will become blastocysts.
This explains why we need 4, 5 or even 6 embryos to be able to identify a “Top-Quality-Embryo”!
For several years now we´ve been performing the blastocyst culture. The result is a very good pregnancy rate (by international standards) and a low rate of twin pregnancies, as we mostly perform a SET (Single Embryo Transfer).