People fail to understand that pregnancy is a very complex process. Even after obtaining healthy eggs and sperms, combining them successfully in a laboratory and putting an apparent healthily dividing embryo into the uterus, there is much that can go wrong. The truth is that even with all the advancements in the fields of science and technologies, what is not known about pregnancy far exceeds what is known.
But the thing is IVF is an emotional, financial and physical roller coaster ride for the couple. Even the people that successfully obtain a baby do so with ease. Only about 40%-50% of the people who try to get a baby do so after the very first chance. There are a few specific factors that have been identified to cause IVF failure. It becomes the responsibility of the physician to look at the root of the cause that is stopping the pregnancy.
What are the causes of IVF Failure?
There are a few important variables that are involved in a successful IVF cycle. These are normal and functional sperms, a healthy egg and a uterus that can nurture the growth of the baby. There are lots of other factors that can impact the chance of pregnancy with IVF. The laboratory environment and the techniques used there also play a role. Even the skill of the specialists who retrieve the egg and transfer the embryo are accounted for.
Abnormalities in the egg
The structure of the human egg is very complex. It is also subject to damage, making it non-functional. When the cell division takes place, the chromosomes separate because of their attachment to a structure, known as the spindle apparatus. The spindle apparatus become fragile with the age of the oocyte. This means the chromosomal distribution can be abnormal and the embryo would be non-viable. It has been seen through studies that as many as 25% to 40% of all the oocytes are actually abnormal and the number increases with the age of the woman.
Abnormalities in the sperm
Abnormal sperm has been seen to be a less common factor in the success of an IVF cycle. However, they do play an important supporting role. The sperms do not just bump into the eggs and result in fertilisation. The process is much more complex. The sperm should be motile and be able to swim towards the egg. There are specific receptors on both the sperm and the egg, that allow their interaction.
The embryo selection methods
The embryologist transfers the embryos into the uterus of the woman. There is a severe limitation when it comes to distinguishing the chromosomally normal embryos from the chromosomal abnormal ones. The embryos are thus selected on the basis of 3 criteria - embryo grade, the cell stage and the rate of cell division. It is known that the embryos that have 6 cells have a much better prognosis than those having 5 or fewer cells.
Factors affecting the lab
The IVF laboratory is an environment that is controlled tightly. The eggs, sperms and embryos are controlled in a manner that would not be different than the insides of the female reproductive tract. Concentrations of oxygen and carbon dioxide are tightly controlled, along with factors like pH, humidity, light and temperature. Even the slightest alterations would result in the death of these tiny beings.
If the initial IVF is unsuccessful, an alternative stimulation regimen and a different IVF protocol need to be followed. Donor gametes or pre-implantation genetic screening might be considered as well. The physician would be able to offer better insights into the matter.