Rocío Núñez Calonge
Scientific Director of the UR International Group and Coordinator of the Ethics Group of the Spanish Fertility Society
his study on a new sperm sex selection technique is written by one of the leading pioneers in assisted reproduction, Professor Palermo, who is credited with the discovery of ICSI or sperm microinjection. It is a well-designed study, with a high number of cases, of good scientific quality. The journal [in which it appears] does not publish papers that are not of high quality.
At first, this did not seem to me to be a very novel topic since, as the authors themselves point out, there are many previous studies on the same subject. The novelty lies in [separating] two groups using preimplantation genetic diagnosis (PGT-A) to study chromosomal abnormalities in the resulting embryos, and in one of the two groups using the proposed sperm selection technique. In this way, the researchers compare the two groups to see whether the sex-specific sperm selection technique is useful and safe, and whether further chromosomal abnormalities are found after its use.
The results of the study confirm that it is possible to select a particular sex with a 80% probability, and safely—since the technique, which is very simple, does not affect the genetic load of the embryo.
The authors propose that this technique could be used both for couples who want to select the sex of the baby out of personal desire and for medical reasons—that is, when there is a risk of disease linked to the sex of the baby. They say this would be more ethical than using pre-implantation genetic testing.
From a purely medical point of view, the use of this technique when there is a sex-linked disease (such as haemophilia) would not be appropriate, as an 80% chance leaves the couple with a 20% chance that the baby will not be of the chosen sex, resulting in a person with the disease. However, if the selection is made purely for personal reasons, this margin of error would be acceptable.
In addition, the authors themselves speak of an important limitation, which is that the sex of the embryo chosen for transfer is not known. It may happen that, among several embryos obtained, although most of them are of the desired sex, the wrong one is chosen. From an ethical point of view, what happens to the rest of the embryos that are not chosen? What would be their fate?
Therefore, it does not seem to solve the possible ethical problems that the use of PGT raises.
In Spain, sex selection is not allowed except for medical reasons. When the law was passed in 1988, this issue was raised on the basis of the possible selection that certain groups could make to the detriment of the other sex, which would lead to an imbalance in the population.
At present, such a ban does not make much sense, as sex selection would be performed by a small group of patients for personal reasons, and would not lead to a population imbalance.
The use of the technique proposed by the authors could be very useful in assisted reproduction centres, as it is very simple (almost the same as what is usually done for the preparation of sperm in laboratories), and could help couples who wish to increase the probability of obtaining a child of the desired sex. However, it is only an increase in this probability. [Couples] should be well informed beforehand and not offered any certainties.