Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 95

Parents have long shown a preference for giving birth to a girl or boy, depending on circumstances such as cultural or religious traditions, the availability of males or females to perform certain kinds of work important to the family or society, or the sex of the couple’s other children. Until recently, the sex of an unborn child was a matter of hope, prayer, and folk rituals. It is only in the past generation that science has made it possible for parents to reliably choose the sex of their unborn child. The introduction of sex selection has been a boon to couples carrying a genetically transmitted disease (i.e., a disease carried on the sex chromosomes), enabling them to have a healthy baby of the sex unaffected by the disease they carried.

Sperm cells can be sorted by whether they carry the X or Y chromosome. Through in vitro fertilization, a zygote with the desired sex is created.

Brain light/Alamy Stock Photo

Sex selection is generally conducted using two methods: preimplantation genetic diagnosis (PGD) or preconception sperm sorting (Bhatia, 2018). PGD creates zygotes within the laboratory by removing eggs from the woman and fertilizing them with sperm. This is known as in vitro (literally, “in glass”) fertilization because fertilization takes place in a test tube, outside of the woman’s body. After 3 days, a cell from the organism is used to examine the chromosomes and determine its sex. The desired male or female embryos are then implanted into the woman’s uterus. PGD is generally conducted only when the risk of family genetic disorders is high and is about 99% effective.

Preconception sperm sorting entails spinning sperm in a centrifuge to separate those that carry an X or a Y chromosome. Because X sperm are denser than Y sperm, they are easily separated. Sperm with the desired chromosomes are then used to fertilize the ovum. Sperm sorting has been available and commonly used since the 1970s. The success rate is about 75% (Bhatia, 2018).

The availability of sex selection procedures enables parents to choose the sex of their child because of personal desires, such as to create family balance or to conform to cultural valuing of one sex over the other, rather than simply to avoid transmitting genetic disorders (Robertson & Hickman, 2013). Critics argue that sex selection can lead down a “slippery slope” of genetic engineering and selecting for other characteristics, such as appearance, intelligence, and more (Dondorp et al., 2013). Others express concerns about societal sex ratio imbalances if sex selection becomes widely practiced (Colls et al., 2009; Robertson & Hickman, 2013). Such sex ratio imbalances favoring males have occurred in India and China because of female infanticide, gender-driven abortion, and China’s one-child family policy (see the Lives in Context: Cultural Context feature in Chapter 12 for more information; Bhatia, 2010, 2018).

Most Canadian, U.K., and European countries restrict the use of PGD and prohibit it for nonmedical reasons (Bayefsky, 2016). The United States does not have a formal policy regarding sex selection (Deeney, 2013). Sex selection remains hotly debated in medical journals, by hospital and university ethics boards, and by the public.