What stops an embryo from growing?

Human biology is a weird and wonderful thing and every sperm, every egg is completely genetically different and each sperm and each egg and each subsequent embryo are completely unique and have their own compatibility and potential and all we can do is put them together and give them the best possible environment for them to reach that potential. Some embryos just don’t have that potential to do anything and that’s why we do classicist culture to select the best embryos and those that have the highest potential of achieving a pregnancy. Just the way human biology is, it’s just one of those things that not everything will go as it should and they just stopped developing.

In this case, the embryos can stop growing. For example, sometimes we see on Day 3 that the problem is the sperm’s quality; in this case, maybe the fragmentation of the DNA of the sperm. This is the most common, but we need to wait until we see how it’s going to be in the culture until Day 5.

Usually embryos don’t stop growing – it’s quite rare to see an embryo arrest which will usually happen on day two of the embryo development. The embryo will grow but quite slowly and not reach the desired stage, for example, the blastocyst. The genetics mostly of the embryo as well as that comes from the quality of the egg and the quality of the sperm are responsible for not allowing the embryo to go one step further, for example, from a day 3 and eight cell embryo to become a blastocyst.