Technology

Sex Selection

Should you be allowed to pick your kid's sex?

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It is sometimes ethical to let parents choose their children's sex, according to John Robertson, acting chairman of the ethics committee for the American Society for Reproductive Medicine. This opinion set off a storm of controversy last week.

Attempts to select children's sex have a long history, from the herbal nostrums recommended by traditional healers to more recent therapists' advice about which forms of intercourse are allegedly likely to produce girls or boys. Sex selection has become a national crisis in India and China, where cheap mobile ultrasound clinics travel the countryside testing pregnant women. Women who discover that their fetus is female often opt for legal abortions. This practice has reportedly skewed sex ratios from the natural 106 boys to 100 girls to as high as 130 boys to 100 girls. Such results led both China and India to ban ultrasound testing for the purpose of sex selection.

In the United States, there is little evidence that abortion is used for the purposes of sex selection. There are, however, a variety of new techniques that can help parents select their next child's sex. Consider flow cytometry, a method for sex selection in farm animals that fertility specialists have now adapted for human beings. This technology tags sperm bearing X chromosomes (those which determine females) and sperm bearing Y chromosomes (those which determine males) with different fluorescent dyes so that they can be segregated into different batches. Once the sperm have been segregated, they may be used in either artificial insemination or in vitro fertilization to produce a child of the desired sex. This MicroSort service was first offered to clients at the Genetics and IVF Institute in Fairfax, Virginia; 10 of the first 11 babies born using it were girls. (Sperm segregation can also help prospective parents avoid giving birth to a male child that suffers from one of the many X-linked genetic diseases, such as hemophilia.) Fertility specialists refer to MicroSort as pre-conception sex selection, or PSS.

In an ethical statement issued earlier this year, the American Society for Reproductive Medicine concluded that if PSS is found to be safe and effective, "physicians should be free to offer pre-conception gender selection in clinical settings to couples who are seeking gender variety in their offspring." ("Gender variety" means that parents would be choosing to have a baby of the sex opposite that of their first child.) The committee added some important caveats, including requirements that patients be fully informed of the risks of failure and that they give assurance that they will fully accept children of the opposite sex should the PSS fail.

And it might fail. The sperm-separating technique is not perfect: Batches of sperm intended to produce males typically contain 73 percent Y chromosome sperm while the female batches contain 90 percent X chromosome sperm. So some fertility doctors want to offer their patients a technique with a nearly 100 percent chance of producing a child of the desired sex: pre-implantation embryo selection. "We will offer it immediately," Norbert Gleicher of the Center for Reproductive Medicine told the New York Times. Gleicher notes that in the last three months alone, some 30 to 40 couples had him asked about this method.

In pre-implantation sex selection, prospective parents' eggs and sperm are combined in a petri dish producing several embryos. Doctors then take a single cell from each embryo and test it to see which chromosome it bears. Only embryos of the desired sex are implanted in a woman's womb. The chances that this technique will result in a successful pregnancy that comes to term are similar to those of in vitro fertilization in general: about 20 to 30 percent. This type of sex selection is not cheap—costs run around $20,000 per attempt.

Abortion opponents who believe that embryos are people naturally oppose this technique, because the embryos of the undesired sex will be destroyed. (Of course, fertility clinics regularly produce embryos that are never implanted and are often destroyed—or, now, could be used in embryonic stem cell research.) Setting aside those arguments, what other concerns do some ethicists have about allowing sex selection, either pre-conception or pre-implantation?

One concern is that the sex selection techniques could lead to a wildly skewed number of males and females in society, resulting in a lot of unhappiness and social unrest. However, unlike in China and India, polls show that Americans generally do not express a strong preference for children of either gender, so most ethicists agree that that is not a major issue here.

Others worry that sex selection is a form of sexism—that is, that it regards one sex as inferior to another. It is possible that some parents in the United States harbor such bigoted notions, but this concern is somewhat allayed by the evidence that 90 percent of couples choosing sex selection are doing it because they wish to have children of both sexes in their families. "Sexism will no more be reinforced by PGS [pre-conception gender selection] or human cloning than it is now by pre- and postnatal gender stereotyping," insists Judith Daar, a bioethicist at Whittier Law School. In other words, if sexism is a problem, the arena in which to address it is society at large, not parents' private reproductive choices.

Some others see the use of pre-implantation sex selection as a slippery slope to eugenics, since the same techniques can be used to test for other genetic traits. They might want to ponder the story of six-year-old Molly Nash, who suffered from the fatal genetic disease Fanconi anemia. The only cure for Molly's disease is a bone marrow transplant from a compatible donor, so her parents used pre-implantation genetic testing to help them bear a sibling who would be a perfect genetic match for her. Using in vitro fertilization, Molly's parents produced 30 embryos that were tested for the disease gene and for transplant compatibility. Only five had the right genetic makeup. The fourth attempted pregnancy resulted in the birth of Adam Nash in August 2000. His umbilical cord blood stem cells were used to replace Molly's defective marrow, and now both children are healthy.

Few people would regard what Molly's parents did as immoral—after all, genetic testing in this case resulted in two valued and healthy children. Sex selection is controversial because it is the first example of genetic selection for a non-disease trait. Being a boy or girl is not a disease.

So should parents be permitted to select traits other than the sex of their children? Few aspects of human development are more significant than one's sex; it's a central fact of one's identity as a human being. If it is ethically permissible for parents to make that choice, the case for letting them make less significant genetic choices for their offspring is already made. (Keep in mind that we are not talking about directly manipulating the genetic makeup of any individual. We're talking about permitting parents to test and choose among embryos for those traits they believe will give their children their best chances in life.)

Australian bioethicist Julian Savulescu is right when he reminds us, "The Nazis sought to interfere directly in people's reproductive decisions (by forcing them to be sterilized) to promote social ideals, particularly around racial superiority. Not offering selection for nondisease genes would indirectly interfere (by denying choice) to promote social ideals such as equality or 'population welfare.' There is no relevant difference between direct and indirect eugenics. The lesson we learned from eugenics is that society should be loath to interfere (directly and indirectly) in reproductive decisionmaking."

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