Answer from: Andrew Thomson, FRCPath
It’s a difficult question to answer and it depends on the embryos really. The first few days up to Day 3 is mainly down to the egg and also the environment that egg is in. So what we would like to see is from that egg from the fertilization stage to develop and cleave into a nice even two cell and then each one of those two cells to divide evenly into a four cells and then, on day three go on to a nice eight cell and then what happens if that eight cell embryo (which is a good quality) when we check it on day five, if it’s still a really nice eight cell quality embryo, it’s then due to in most cases due to the sperm because the sperm have to flick a switch within that embryo called the embryonic genome and that allows the embryo to pass that first checkpoint to make a blastocyst. Now the sperm can only do that, if that embryo is in a good enough place to actually do it. If that egg has not developed well, from the fertilization stage and it’s a two cell that fragmented and then maybe done some direct cleavages so sort of like chewed and those two cells split into more than two cells and that embryo is not in a good place, the sperm doesn’t have the best chance of actually flicking that switch because it’s not that embryo isn’t really compatible with going to a blastocyst. It does still sometimes happen but it’s just one of those things. If you see lots of good embryos on Day 3 and the blastocyst formation rate is reduced so say under 50%, then it could be a sperm issue and we should maybe be looking at sperm DNA fragmentation if actually the embryo development wasn’t good to Day 3 and we’re not getting blastocyst formation then that’s more than likely a egg issue. So again it’s very patient to patient.
Answer from: Dimitris Papanikolaou, MD
I believe that the egg is 80% responsible for a successful pregnancy, the sperm comes to about 20% and after that, all the external factors including immune system, the anatomy and the others can change those possibilities. But I believe that the egg factor is the most important.
Answer from: Alejandro Aldape Arellano, MD
When we are talking about embryo quality, we have to consider not only the egg but also the sperm. We can divide the internal quality of the embryo into genetic quality and energy quality. The external quality refers mainly to what we can see about the embryo. And then, we can talk about the morphological quality. To grade this, we can assess the expansion, the number of cells that are in the trophectoderm, and also the inner cell mass. All of this is going to give us external quality.
The internal quality of the embryo would the most important, so the genetic and the energy one. Genetic quality is mainly influenced by age. It refers mostly to the situation when a patient is over 40, and the internal quality of the embryo can be potentially compromised. We can check the internal quality with the genetic investigation, such as PGS (pre-implantation genetic screening), and see if all the chromosomes are there. Of course, we still don’t have the investigation for checking the energy of the embryo.
When it comes to external factors that may influence the quality of the embryo, the two most important ones would be the culture medium and the laboratory of IVF, as well as the incubator we are using for the IVF cycle. And for that reason, it is mandatory to go to the clinic where they have all the accreditations and best standards. In terms of the genetic investigation, we are using the PGS and the PGD. With these, we can assess all the chromosomes in the embryo and ensure that the embryo we are going to transfer is completely normal.
When we are talking about embryo quality, it is a little more complicated. We need to take into consideration the sperm quality as well. We need to assess the sperm quality in advance before going to the treatment. In order to do this, we need to check the DNA fragmentation and take the FISH test. If both are completely wrong and the outcome is poor, the recommendation would be to proceed to the treatment and do genetic testing into the embryo.
Answer from: Inna Moroz, MD
The quality of embryos can be influenced by numerous conditions. The most important one is the age of a person. The older the woman, the worse the situation. The embryos can develop genetic abnormalities. Even the performance of ICSI embryos can inhibit the formation of blastocysts.
The second important factor is the quality of the sperm. The poor sperm quality but the high DNA fragmentation can harm the development of healthy embryos and healthy fetus. The third very important factor is the cultivation conditions in the laboratory. The early stages of embryo development have a lot of important processes. If you have a rare cultivation condition, the embryology lab is very crucial. Even the fertilization time is very important for blastocyst formation.
It is also worth mentioning that the appearance of the embryo and the genetic content is very related. But sometimes, even medium quality embryos can create normal pregnancy.
Answer from: Olena Bondzyk
The embryo quality is the most important for the successful IVF cycle. Many factors can influence embryo development and quality. I want to highlight the most significant ones. The first one is the quality of male and female gem cells. If oocytes or sperm have poor quality, the embryos probably will be of poor quality, too. Oocyte quality depends on age, ovarian reserves stimulation protocol, health, weight, and lifestyle of a woman. Sperm qualities such as quantity and motility can decrease by obesity, stress, bad habits, etc.
As you see, the second factor influencing the embryo is the patient’s lifestyle. But fortunately, you can control your lifestyle, and this bad influence can be improved. The third factor is the attentive realization of doctors’ recommendations during treatment. All protocols are individual in timing and doses, so your doctor will choose the best protocol for you.
The next group of factors is genetic factors. If you have reasons for pre-implantation genetic diagnosis (PGD), you should do this procedure. PGD allows you to choose a healthy embryo for embryo transfer. The next point is manipulations with gametes and embryos, such as ICSI, cryopreservation and thawing, biopsy, etc. Your embryologist must be highly qualified and have good work experience. The last factors I want you to know are the conditions of embryo cultivation. Your IVF clinic must have modern equipment and use high-quality culture media for every protocol and procedure.
In conclusion, I want to emphasize that abnormalities in the embryos are the reasons for about 60% of all miscarriages. Transferring the best quality embryo during your IVF treatment increases your chances for a successful pregnancy.
On what basis is the quality of embryos defined, and what factors decide on embryo quality?
When embryo quality is to be described, it’s not only the egg but also the sperm. We can divide these factors into two groups and analyze the internal and external quality of the embryo. What is what? Can embryo quality be improved?