Ethical concerns about the ethics of selecting the sex of a child predate current techniques of prenatal genetic diagnosis (PGD) and sperm sorting. The only methods previously available were highly problematic, as they involved infanticide or abortion of an unwanted sex. PGD is less problematic than the earlier methods, yet still troubling to some because it involves destruction of a healthy embryo and risks to women. The technique of sperm sorting, still in an experimental phase, is the least ethically problematic method, yet opponents argue that sex selection by any means involves sex discrimination and can have undesirable consequences. One such consequence is an imbalance in the sex ratio. This imbalance already exists in some Asian countries that favor male children, but is less likely in Western Europe and North America. There is increasing acceptance of family balancing as a reason for sex selection, but some people remain opposed to broadening the indications for sex selection of offspring beyond family balancing. Nevertheless, parents may have good reasons other than family balancing for choosing the sex of a future child. Such reasons may be justified by the principle of reproductive liberty.