Egg donation is the Assisted Reproduction treatment with which the best pregnancy rates are achieved, reaching over 90% after two attempts. However, egg donation does not guarantee pregnancy. Below, we will try to explain why this treatment does not always work.
What is egg donation?
Ovodonation is an in vitro fertilization (IVF) treatment in which we use oocytes from a healthy, young donor to generate the embryos that we will later transfer into the uterus of the recipient woman. It is indicated in cases in which the patient cannot or it is not advisable to use her own eggs (absence of ovaries, low ovarian reserve, poor oocyte quality, genetic alterations, absence of pregnancy after several IVF cycles).
Egg donors are young (under 35 years of age) and healthy women. This means that their eggs are of high quality and, therefore, the embryos generated from them have a high probability of producing pregnancy. However, although the oocyte is a crucial factor in determining the success of an Assisted Reproduction treatment, it is not everything. There are other factors that determine the implantation capacity of an embryo and that determine whether or not pregnancy occurs.
Factors that affect the success of ovodonation.
Male factor:
The age of the male influences the quality of the spermatozoa. In most of the couples who undergo egg donation treatment, the male is over 44 years of age and this translates into a poorer quality of his gametes with a higher rate of chromosomal abnormalities in them.
On the other hand, there are other alterations in the spermatozoa that cannot be diagnosed in a normal semen analysis and, nevertheless, can significantly affect the probability of pregnancy.
Sperm DNA fragmentation is an indicator of the degree of oxidative damage to sperm DNA. When fragmentation is high (more than 30%), the probability of pregnancy can be less than 2%. At URH García del Real we systematically perform a sperm DNA fragmentation study on all couples who are going to undergo egg donation treatment and, if it is high, we have different strategies to reduce it and thus increase the probability of pregnancy.
The effect of the male factor on embryo quality is mainly observed between the 4th and 5th day of embryo development. For this reason, long embryo culture up to the blastocyst stage will give us a lot of information about the possible presence of a male factor, and will help us to select the embryos with the highest implantation potential.
At URH Garcia del Real, in all egg donation cycles we do the embryo transfer at the blastocyst stage.
Uterine factor:
In order for an embryo to implant, a good dialogue between the embryo and the endometrium is essential. We still have a lot to learn about embryo implantation, but we know that there are certain things that can hinder the implantation capacity of an embryo.
The thickness and appearance of the endometrium is critical to implantation. In most cases, treatment with estrogen and progesterone allows us to achieve an adequate endometrium. However, in other cases it is not so easy and we need to combine different therapeutic strategies to achieve this. If we do not achieve an optimal endometrium it is preferable to freeze the embryos and defer the embryo transfer.
Endometrial polyps, the presence of submucosal or intramural fibroids that deform the uterine cavity, septa or septa in the uterus, hinder the correct implantation of the embryo. At URH Garcia del Real before an egg donation cycle we always do an exhaustive study of the uterus to rule out this type of alterations.
Infectious or inflammatory pathology of the endometrium (endometritis) can also decrease the probability of pregnancy. Endometritis is a pathology that, in most cases, can go unnoticed. For this reason, in patients who have not achieved pregnancy after an egg donation cycle, it is important to take an endometrial biopsy to rule out an alteration of this type and, if it exists, to be able to treat it.
Other aspects such as the genetic expression of the endometrium during the implantation window or the role of the endometrial microbiota in implantation are being studied. More scientific evidence is still needed to reach solid conclusions in this area.
Systemic alterations in implantation failure
- Coagulation disorders (thrombophilias): although for a long time a very important role has been given to coagulation disorders in patients with implantation failure (who have not achieved pregnancy after successive transfers of good quality embryos), nowadays it is being questioned whether thrombophilias are responsible for implantation failure.
- Immunological alterations: the immunology of reproduction is also being studied. Multiple treatments have been postulated to correct possible immunological disorders and their impact on implantation, however, we still lack sufficient scientific evidence to be able to recommend these treatments.
Lifestyle to promote pregnancy
There are multiple factors in our daily life that will condition the probability of pregnancy. Being overweight, smoking, alcohol consumption, decrease the probability of pregnancy and increase the risk of miscarriage. Maintaining a healthy lifestyle, doing sports, following a balanced diet and eliminating the consumption of tobacco and alcohol, is essential to have a good health and increase the probability of pregnancy.