Читать книгу Bioethics - Группа авторов - Страница 62

Interest in sex selection has a long history dating to ancient cultures. Methods have varied from special modes and timing of coitus to the practice of infanticide. Only recently have medical technologies made it possible to attempt sex selection of children before their conception or birth. For example, screening for carriers of X‐linked genetic diseases allows potential parents not only to decide whether to have children but also to select the sex of their offspring before pregnancy or before birth.

Among the methods now available for prepregnancy and prebirth sex selection are [1] prefertilization separation of X‐bearing from Y‐bearing spermatozoa (through a technique that is now available although still investigational for humans), with subsequent selection for artificial insemination or for IVF; [2] preimplantation genetic diagnosis (PGD), followed by the sex selection of embryos for transfer; and [3] prenatal genetic diagnosis, followed by sex‐selective abortion. The primary focus of this document is on the second method, sex selection through PGD, although the issues particular to this method overlap with the issues relevant to the others. Preimplantation genetic diagnosis is used with assisted reproductive technologies such as IVF to identify genetic disorders, but it also can provide information regarding the sex of embryos either as a by‐product of testing for genetic disorders or when it is done purely for sex selection (Table 9.1).

As the methods of sex selection have varied throughout history, so have the motivations for it. Among the most prominent of motivations historically have been simple desires to bear and raise children of the culturally preferred gender, to ensure the economic usefulness of offspring within a family, to achieve gender balance among children in a given family, and to determine a gendered birth order. New technologies also have served these aims, but they have raised to prominence the goal of avoiding the birth of children with sex‐related genetic disorders.

Table 9.1 Embryo sex identification by preimplantation genetic diagnosis for nonmedical reasons

(a)	Patient is undergoing IVF and PGD.
	Patient learns sex identification of embryo as part of, or as a by‐product of, PGD done for other medical reasons.
(b)	Patient is undergoing IVF and PGD.
	Patient requests that sex identification be added to PGD being done for other medical reasons.
(c)	Patient is undergoing IVF, but PGD is not necessary to treatment.
	Patient requests PGD solely for the purpose of sex identification.
(d)	Patient is not undergoing either IVF or PGD (for the treatment of infertility or any other medical reason).
	Patient requests IVF and PGD solely for the purpose of sex identification.

Whatever its methods or its reasons, sex selection has encountered significant ethical objections throughout its history. Religious traditions and societies in general have responded with concerns varying from moral outrage at infanticide to moral reservations regarding the use of some prebirth methods of diagnosis for the sole purpose of sex selection. More recently, concerns have focused on the dangers of gender discrimination and the perpetuation of gender oppression in contemporary societies.

This document’s focus on PGD for sex selection is prompted by the increasing attractiveness of prepregnancy sex selection over prenatal diagnosis and sex‐selective abortion, and by the current limited availability of methods of prefertilization sex selection techniques that are both reliable and safe. Although the actual use of PGD for sex selection is still infrequent, its potential use continues to raise important ethical questions.

Central to the controversies over the use of PGD for sex selection, particularly for nonmedical reasons, are issues of gender discrimination, the appropriateness of expanding control over nonessential characteristics of offspring, and the relative importance of sex selection when weighed against medical and financial burdens to parents and against multiple demands for limited medical resources. In western societies, these concerns inevitably encounter what has become a strong presumption in favor of reproductive choice.