Whilst it is technically possible to choose a child’s gender using pre-implantation genetic diagnosis, Spanish law prohibits selecting a baby’s sex, except with a view to avoiding the transmission of genetic diseases associated with the X chromosome. Such is the case, for example, of haemophilia A.
Law 14/2006 indicates that pre-implantation genetic diagnosis may only be used in order to detect serious genetic diseases or those which compromise the viability of an embryo. Therefore, this technique may not be used in order to select a future baby’s gender. Any other use of this technique is a serious offence which is punishable by law.
Although it is permitted in other countries, Spanish legislation does not explain why gender selection is forbidden. However, there are a number of possible reasons.
The first is the potential for gender imbalance within the population. This is not a very strong argument because it is based on the presumption that most parents would opt for the same sex. This argument is based upon little rationale in Spain since one particular gender is not valued more than the other nor provided with greater incentives for parents, as might be the case in countries such as China.
Another explanation people give is that, in selecting gender, we would be entering into practising medicine that is not aimed at curing patients but which is on-demand medicine. This may well be true, but it is also true of plastic surgery, for example.
Doubts also arise regarding what would would be done with the embryos of the unwanted gender since we need to take into account that these would be healthy embryos. I believe that the answer to this question is the same as in the case of surplus embryos following treatment in which gender has not been selected. That is, the parents choose one of the options available to them by law: donate them to other couples for use in reproduction, donate them for research or rule out their use for any other purpose (taking into account all legal implications).
One last reason to point out is the possibility that reproductive medicine would become commercialised since patients without fertility issues would turn to these techniques based exclusively on the fact that they would be able to choose the gender of their child.
Whatever the case, this is a controversial matter since it touches on ethical and moral issues. Proof of this is that, in recent times, there have been several initiatives aimed at changing the Law in order to permit choosing gender and all of them have been unsuccessful.