Answer from: Raúl Olivares, MD
In regard to the standard figures of a normal IVF. In our centre, we know that 80% of eggs that we collect are going to b metaphase II, which means mature. These are the eggs that are suitable for being inseminated with the sperm. From this 80%, again 80% is going to be normally fertilized, so that’s the number of 2 PN or 2 pronuclei, which are the normally fertilized eggs that we expect from the initial pool of mature eggs.
Out of this 80% of fertilized eggs, the number of blastocysts is going to depend a lot on the age of the patient. For example, in the egg donation, we consider it normal to have something between 60 to 70% of the embryos becoming the blastocyst, but if you are working with a patient who is 43 years old, this percentage maybe even zero. There could be an embryo factor.
In standard circumstances, when we think that the egg is not the problem and there is no severe male factor, you should expect that 50-60% of the embryos are going to reach the blastocyst stage.
What is the average number of oocytes becoming a day-5 blastocyst?
The day-5 embryo, so-called blastocyst consists of hundreds of cells, is highly developed and is well-suited to implant. Only about one-third of them can develop to this stage. Will my embryos make it to day-5? What percentage of fertilized eggs fail to develop?