Deborah Leavy | THE NEXT ABORTION DEBATE

THE DECISION to have an abortion is usually the result of pregnancy unwanted by women in difficult circumstances: young, single, in school, in abusive relationships, victims of rape or incest. There are many reasons women feel they are not in a position to raise a child at a certain point in their lives and come to this difficult choice.

As the science of genetic testing has advanced, another model has emerged in which abortion has become an option for planned and wanted pregnancies as well.

Genetic testing was once a somewhat risky procedure performed late in pregnancy, recommended only for older women at greater risk of bearing children with chromosome damage. Now, a simple test is available early in the first trimester that lets parents know whether their child might have disorders like Down syndrome, sickle-cell anemia, cystic fibrosis or a host of other problems that may mean severe disabilities or a shorter life span.

If you knew that your pregnancy would result in a child with Down syndrome, a form of mental retardation, would you choose abortion? An estimated 90 percent of those faced with the prospect do just that.

But, following the law of unintended consequences, parents of Downs children are now worried that there may be fewer services for their children if there are fewer Downs children being born.

Just as polio vaccines made it rare in the developed world, genetic testing may mean fewer children with devastating conditions.

Some advocates for the disabled are horrified at the prospect that there may be fewer of the disabled to advocate for their rights. Some parents are even trying to persuade pregnant women to bear and raise Downs children so that their own children will benefit. As lovable as these children may be, I can't imagine wishing this fate on other parents, for any reason.

As we wrestle with the ethics of genetic testing, diagnosis is moving to an even earlier stage, from fetal to embryonic. By using in vitro fertilization in a lab, doctors can remove one cell from an eight-cell embryo to determine if it carries an unwanted genetic trait. This is especially important to couples who don't want to pass on inherited characteristics like increased risk of breast cancer, or the genes for a rare colon cancer. They can pick an embryo without the trait.

This is an expensive (and uncomfortable) procedure. But as the price comes down, it may become more common. And it's raised the fear that we will enter an era of "designer babies," embryos chosen like consumer goods for superficial reasons.

"The genetic revolution brings challenges to liberals and conservatives," says Art Caplan, head of the department of medical ethics at Penn. "We have to confront the fact that some choices may be vain and selfish, while others are grim decisions to avoid devastating conditions."

There no doubt will be some reasons for abortion that I'll disagree with. So will you. And if there is to be a line, who should draw it?

So the new abortion debate is much like the old one: The question is, who decides?

The question of whether and when to bear a child is one of the most personal you can make. For the government to make that decision smacks of a totalitarian state.

"Screening for reasons is not an appropriate role for the state," says Anita Allen, professor of law and philosophy at Penn law school. "You have to trust women and families to make good decisions about abortion."

In fact, there is no evidence that people are making this decision for frivolous reasons. Hypothetical questions about choosing blue-eyed babies over brown, tall over short, are just that - hypothetical. The number of abortions is down. Genetic testing is pro-family, allowing couples who fear passing on destructive genes to have healthy children.

I do worry that, as people of means are able to opt out of having children with devastating conditions, only poor people, including those in developing countries, will have them. Already, few U.S. babies die of diarrhea, malnutrition or malaria.

But the answer to that disparity shouldn't be forcing parents to bear disabled children. We have to be realistic about the burden of care, and rather than judging, say, "There but for the grace of God go I."

Of course, every parent knows that having children will continue to be unpredictable. You take a chance when you become a parent. But it is good to know we can reduce the odds on some of the most heartbreaking results. *

Deborah Leavy is a public policy consultant who contributes regularly to the Daily News. E-mail her at deborah.opinion@gmail.com.