Gender and Genetics
Sex Selection and Discrimination
Sex selection refers to the practice of using medical techniques to choose the sex of offspring. The term “sex selection” encompasses a number of practices including selecting embryos for transfer and implantation following IVF, separating sperm, and selectively terminating a pregnancy. The topic of sex selection is particularly relevant to a discussion on gender and genetics because genetic technologies and services may be used to preferentially choose one sex over the other. Sex selection has a wide range of ethical, legal and social implications. A significant ethical concern is that sex selection for non-medical reasons will reinforce discrimination, particularly against women.
The are three core motivations for engaging in sex determination and sex selection:
- medical reasons—such as preventing the birth of children affected or at risk of X-linked disorders.
- family balancing reasons—where couples choose to have a child of one sex because they already have one or more children of the other sex.
- gender preference reasons— often in favour of male offspring stemming from cultural, social, and economic bias in favour of male children and as a result of policies requiring couples to limit reproduction to one child, as in China.
Ethical Issues Raised by Sex Selection
Sex selection for non-medical reasons raises serious moral, legal, and social issues. The principal concerns are that the practice of sex selection will
- distort the natural sex ratio leading to a gender imbalance and
- reinforce discriminatory and sexist stereotypes towards women by devaluing females.
In some countries, such as India and China, it is commonly known that the practice of sex-selective abortion has resulted in distortions of the natural sex ratio, in favour of males. In addition, there is concern that sex selection involves inappropriate control over nonessential characteristics of children and may place a potential psychological burden on, and hence cause harm to, sex-selected offspring. (75)
Different ethical concerns are raised depending on the type and timing of sex selection and whether or not it occurs in sperm or embryos. The development of effective prenatal diagnostic tools, such as chorionic villus sampling (CVS), amniocentesis and ultrasound in the 1970s made prebirth gender identification a reality. (76) In the early 1990s, preimplantation sexing of embryos for transfer following in vitro fertilization (IVF) was developed, enabling highly reliable preconception sex selection. (77) More recently, sperm separation by flow cytometry has enabled a less invasive method of sex selection. (78)
Sex selection by sperm sorting or flow cytometry enables the separation of X- from Y-chromosome-bearing sperm due to slight differences in weight (whereby X and Y-bearing sperm have a DNA difference in content of approximately 2.8%). (79) Sexed sperm are then used to fertilise the egg, either in vitro or in vivo (for example, through artificial insemination techniques). The first child conceived from sorted human sperm bearing the X chromosome was born in 1995 to a family carrying the X-linked disease hydrocephalus. (80) As of January 2004, 419 children have been born using sperm separation technology in the United States of America; 91% of offspring using X-enriched sperm were female and 76% of offspring using Y-enriched sperm were male. (81)
Although preconception sex selection methods do not destroy embryos or foetuses and are not as invasive as prenatal or preimplantation sex selection, these procedures still raise important ethical concerns. One concern is that such techniques may reinforce gender discrimination by either allowing male offspring to be produced as first children or by encouraging parents to pay greater attention to gender itself. (82) Still, it has been reported that among couples seeking sex selection via sperm sorting in the United States of America, where the service is only available for medical or family balancing reasons, 90% of couples reported engaging the service for family balancing and 80% of these couples desired girls. (83)
Currently, the principal reliable techniques for sex selection are limited to post-fertilization methods. The technique of preimplantation genetic diagnosis (PGD), employed in assisted reproduction before the transfer of embryos fertilized in vitro, enables blastomere biopsy of one or more cells from a developing embryo at the cleavage or blastocyst stage to ascertain sex. (84) In contrast to sperm sorting, PGD provides nearly 100% accuracy for selecting either sex. Still, because PGD requires in vitro fertilization (IVF), the practice of sex selection via PGD has been primarily used by persons trying to avoid having children with X-linked disorders. (85) For example, approximately 50% of male children born to women who are carriers for haemophilia will have this condition. In order to ensure that offspring do not have this condition, some women at risk of transmitting haemophilia choose not to transfer male embryos following IVF.
Sex selection through prenatal diagnosis followed by selective abortion has existed since the 1970s. Established postimplantation techniques to determine fetal sex during pregnancy include ultrasound, chorionic villus sampling (CVS) and amniocentesis. In addition, karyotyping of fetal cells provides information about fetal sex. These postimplantation methods of sex determination, followed by abortion between eight and twenty weeks gestation, represent the most commonly used methods of sex selection.
In most societies, where sons are preferred for cultural and economic reasons, the preference for male offspring can manifest in a number of ways ranging from differential allocation of household resources and medical care, to neglect of female offspring and female infanticide. (86) Attempts to eradicate son preference in India by legal prohibition of sex selection have not succeeded. (87) In order to address the practice of sex selection, the Indian government introduced the Prenatal Diagnostic Techniques (Regulation and Prevention of Misuse) Act (88) in 1994 which limits the use of prenatal diagnosis to a list of selected congenital conditions and prohibits using these techniques for sex determination of the fetus. (89) These regulations, however, have not been strictly enforced. (90) The Supreme Court of India has issued detailed directives to the national and state governments to raise awareness on the law on sex determination and for increased surveillance of all clinics providing ultrasounds. (91) In 2001, the national sex ratio in India was 933 females to 1000 males, but only 927 females in the age group under six years old. (92) In Haryana state, this discrepancy increased to 861 females to 1000 males, with only 820 females in the under six age category. (93)
Dahl et al. conducted a survey in Germany to ascertain whether there was both a significant preference for children of a particular sex in Germany and a considerable demand for preconception sex selection. (94) They surveyed 1094 men and women between the ages of 18-45 years about their gender preferences and whether or not they would consider selecting the sex of their offspring via sperm sorting followed by intrauterine insemination. Fifty-eight percent of respondents did not express a preference about the sex of their offspring, 30% desired a family with an equal number of boys and girls, 4% would prefer more boys than girls, 3% more girls than boys, and 1% each for exclusively boys or girls only. For first born children, however, they still observed a slight preference for boys over girls (14.2% versus 10.1%). Only 6% of Germans surveyed could imagine taking advantage of preconception sex selection. Moreover, they observed that even in the hypothetical situation that a drug to select for sex became available, 90% stated that they would not use it. Dahl et al. concluded therefore that the availability of preconception sex selection for non-medical reasons is therefore unlikely to cause severe sex imbalances in Germany.