Gender selection: ethical, scientific, legal, and practical issues.

Purpose: This work offers an overview of the technology available and assisted reproductive technology (ART) practitioner attitudes to human reproductive sex preselection in either sperm with the use of flow cytometry (FC) or in embryos by means of preimplantational genetic diagnose (PGD) together with an analysis of Spanish legal environment.
Methods: A review of the legal, ethical and technical literature of the methods to select the sex in the offspring is performed.
Results: Sex selection in humans has different utilities to be employed depending on each country's law. Moreover, different ethical concerns are raised depending on the type of sex selection, in sperm or embryos. Both methodologies to pre-select the sex are trustworthy, with a high predictive power in the determination of the sex, but nevertheless, PGD is better than FC selection in this aspect.
Conclusions: After a careful analysis of ethical, legal, and scientific features of gender selection, FC combined with PGD appears to be the most acceptable way to select the sex of the progeny whatever the circumstances are.