Pre-Implantation Genetic Diagnosis: Should Our Laws Allow Parents to Pre-Screen Their Children?

A week ago, the New York Times reported that aspiring parents of a certain age are increasingly using a relatively new screening technology to maximize their odds of having a child. The technique - called pre-implantation genetic diagnosis (PGD) -- can help prevent miscarriage due to genetic anomalies. Fertility doctors employ PGD in conjunction with in vitro fertilization (IVF), to test embryos after fertilization and select the healthiest ones for implantation in the mother.

Preliminary reports suggest that this technology could spare couples the years of heartache that result from one miscarriage after another, and it may enable some who have given up hope to produce their own biological offspring.

By allowing doctors to select which embryos to implant, however, PGD raises an ethical question that could ultimately become a legal question: What happens when the technique is used, not to avoid miscarriages, but to prevent couples from having abnormal children?

Familiar Questions: Is Eugenic Abortion Ethical? Does It Devalue the Disabled?

This ethical question is, of course, not a new one. When pregnant women undergo a standard amniocentesis, their purpose is to learn whether the child they are carrying is genetically defective in some way. Most commonly, they wish to find out whether their child has Downs Syndrome, a condition that results from a zygote's having an extra copy of the twenty-first chromosome. A positive test result frequently will lead the woman to terminate her pregnancy (indeed, that is ordinarily the purpose of having the test in the first place).

In response to eugenic abortions of this sort, pro-life groups have challenged people to consider the morality of selectively terminating pregnancies involving "undesirable" fetuses. In a poster produced by Feminists for Life, for example, a physically disabled man (whose disabilities presumably result from a genetic anomaly) appears with the caption "Would you say that to my face?"

The implication is that by aborting a fetus with a genetic disorder, a pregnant woman communicates an insulting and disturbing value judgment about the lives of existing children and adults who live with such disorders: that it would be better if they had never been born.

PGD Versus Eugenic Abortion

In some ways, PGD is a more ethical method of screening out Downs babies than the second-trimester abortions that follow a disappointing amniocentesis result. Such abortions involve the killing of a growing fetus because he or she is likely to be mentally retarded and otherwise impaired; in contrast, PGD allows parents to choose the healthiest embryos for implantation. Since some embryos will generally be left behind no matter what the parents' decision, and because the embryo is still a microscopic ball of undifferentiated cells at the relevant time, selective implantation seems less like a form of targeted euthanasia than does selective abortion.

It may, however, be precisely the relative moral ease of PGD for the individual that raises new bioethical issues for our society - and potentially, if our government regulates the use of PGD, new legal issues as well.

If Widely Used, PGD May Have Profound Societal Consequences

As long as amniocentesis (or the less accurate alpha-fetoprotein test) requires a late-term abortion to effectuate a family's eugenic goal, people with Downs Syndrome will continue to share our planet.

In some cases, women will choose to forego amniocentesis altogether - often against the advice of an obstetrician. Some would rather "play the odds" than take even the small risk of miscarrying a healthy pregnancy as a result of the testing procedure.

Meanwhile, other pregnant women believe that abortion is wrong and would therefore carry their pregnancies to term, almost regardless of the expected outcome. And still others feel that if they are pregnant with an impaired child, then perhaps that relationship - despite the considerable pain involved - was meant to be. Because they want to have a baby, they worry that it would be disloyal to a child to place conditions on her rightful place in the family. To abort because a woman does not want to have a child is one thing, they might feel, but to abort because a woman does not want to have "that" child could seem far more invidious.

Once PGD becomes more widely available and affordable, however, many of thequalms that currently prevent eugenic abortion could become moot.

Far from presenting a risk of miscarriage, the decision to undergo PGD may make a successful pregnancy more likely. Furthermore, many people who believe that the decision to abort is wrong do not feel the same way about the decision not to implant a particular embryo, because the embryo is at such an early stage of development and because it is not yet inside anyone's body. And finally, prior to implantation, a woman may not yet feel "attached" enough to an embryo with Downs Syndrome to ask the doctor to implant that one, rather than the other one with no obvious impairments.

In light of these contrasts, then, PGD raises the possibility that one day, no one with Downs Syndrome will be born at all.

A World Without Downs Syndrome: When, and Why, Would It Be Wrong?

Some might ask "So what? Would that be such a terrible thing?"

The answer may depend on why the syndrome has been eliminated. I expect that few would have moral objections to a diet or exercise regime that reduced or eliminated the mutation that causes Downs Syndrome. This would mean that people who would have been born with Downs would now be born with the usual compliment of chromosomes. In a way, they would be the very same people, but without Downs Syndrome (that is, assuming a person could still have his or her identity intact without Downs Syndrome - something that Downs advocates might challenge).

Such a development would be akin to performing genetic therapy on embryos that would otherwise have been impaired. Through such therapy, a person who might have had hemophilia or sickle cell anemia would be born with the capacity to produce clotting factor or red blood cells that carry sufficient iron.

What PGD offers, however, is something quite different. It promises to eliminate not gene mutations, but particular types of people (who carry those mutations) from the population.

Eliminating People Versus Mutations

To understand the distinction I draw, consider the following hypothetical conversation between a mother of a genetically impaired child and her son:

Mother: "Sweetheart, I love you so much. I know there are things you would like to be able to do but cannot. It is because when you were growing inside me, before you were born, doctors did not yet know how to help you."

Son: "Can they help me now?"

Mother: "No. It's the kind of help that you can get only when you're a tiny mass of cells, before you're really 'you' yet. But I love you and will help you do the best you can with what you have."

That conversation makes sense. Had gene therapy been available, the mother could perhaps have had the faulty chromosome removed (or changed) before implanting the embryo in question. The son would have been formed by the same combination of egg and sperm, without the mutation that caused his particular condition.

Consider now a very different conversation:

Mother: "I love you very much sweetheart, but I would have implanted a different embryo if pre-implantation genetic diagnosis had been available to let me know that you would have this condition."

Son: "Then I would not have had the condition?"

Mother: "Well, you would never have been born at all, and I would have had a different child who would not have suffered from the condition. I would have chosen not to implant your embryo at all, so there would have been no 'you.'"

Son: "Oh. I'm sorry I was born."

Mother: "No. Not at all, honey. I love you just the way you are."

One hopes that this conversation would never take place. People speak of PGD "preventing" a child from being sick or deformed, but it does so only in the sense that it helps parents "prevent" the child from coming into existence at all.

One can much more easily imagine oneself healthy than imagine oneself out of existence, replaced by a healthier person. For a parent to tell a child that he or she should have been "prevented" is cruel and aggressive - it is not at all like saying "I wish that you were healthy," when the child wishes the same thing, and the parent's desire comes from empathizing with her own baby.

When the Child Is Happy He Was Born, But Society Is Not: The PGD Worry

In the case of some detectable genetic conditions, life for the child could be so awful that he or she might have truly been better off never coming into existence in the first place.

A child suffering from Tay Sachs disease, for example, lives only a few years and suffers a terrible, painful death in which he or she eventually becomes blind, mentally retarded, paralyzed, and unresponsive to his or her environment. Many would consider the use of PGD to prevent the birth of such children a mercy rather than an attempt to eliminate "undesirables" from the race.

People with Downs Syndrome, by contrast, report that they are happy to be alive. Some have specifically opposed therapeutic abortion on the ground that it suggests -- wrongly, in their view -- that parents of children like them would have been better off childless, or that they themselves would have been better off never being born. Their existence, they feel, was a great gift to them and to those around them, and they are glad that their mothers did not abort.

Could PGD Radically Change Our Population?

Unlike eugenic abortion, then, PGD offers the possibility of radically altering our population. While there will probably always be women who opt to go through with a pregnancy, even when there is a genetic anomaly, it is hard to imagine many women choosing to implant a genetically impaired embryo instead of a healthy one.

Why not give the healthier child an opportunity to exist rather than deny it in place of the impaired one? Few parents, given the choice, would decide to implant the embryo that would give rise to an impaired child.

The dilemma thus arises from the fact that at an individual level, a late-term abortion is a much more difficult moral choice than the use of PGD to select a healthy embryo for implantation.

The level of guilt that a woman will feel if she uses PGD is likely to be fleeting and insignificant compared to what she would feel about a late-term, eugenic abortion. She may even say to the doctor, "Don't tell me about any anomalous embryos -- just implant the healthy ones."

Such an option, however, is unavailable for a woman receiving an amniocentesis: She will know if her fetus is likely to be a Downs Syndrome child, and she will be directly and bluntly confronted with the decision whether or not to abort. Her choice, moreover, will not be between two possible children, but between this living child in her womb right now, and no child at all.

Is PGD A Slippery Slope Toward Weeding Out "Undesirables"?

In sum, at the level of the entire population, the consequences of PGD are likely to be much more dramatic than the consequences of amniocentesis and late-term abortion of genetically impaired offspring. Since PGD is a much easier option, emotionally and morally, people who use it will virtually always (if not always) reject an impaired embryo. And this means that society could come to think of people with Downs Syndrome and other genetic impairments as mistakes that should never have been made.

People with Downs Syndrome deserve the respect and kindness of their fellow human beings. To ensure that they have it, our society must think carefully about whether to permit the use of a technology that promises to screen such people out of the population.

To the extent that some did remain with us, even under a PGD regime, their status as pariahs would be nearly guaranteed. And to the extent that PGD's promise were fulfilled, our eyes might turn next to other "undesirables," ripe for screening in a scientist's laboratory.