There are four states in the nation where it’s illegal to abort a fetus because of its sex. Randy Minchew would like to make it five.

The Leesburg Republican, a lawyer running for Virginia’s House of Delegates, says he will push to outlaw what’s known as “sex-selective abortion” if elected.

But while the practice is widespread in some Asian countries where cultural and political forces drive a strong preference for sons, there’s some debate about the extent to which Americans are using abortion for sex selection.

Some research suggests that it is happening, at least among Asian immigrants. In any case, the practice is becoming a new front in the nation’s abortion battles.

“It’s clearly one of the new types of regulation that the pro-life movement, or at least factions within it, are pursuing,” said Neal Devins, an expert on abortion law at the William & Mary Law School.

The debate over a ban — approved in Arizona, Illinois, Oklahoma and Pennsylvania and proposed in five other states this year — would be a new one in Richmond. Although abortion issues are a staple of General Assembly sessions, legislation concerning sex-selective abortion has never been formally proposed, veterans of local abortion politics say.

“We have not seen that kind of legislation introduced in Virginia,” said Jessica Honke, director of public policy for Planned Parenthood Advocates of Virginia.

Olivia Gans, president of the Richmond-based Virginia Society for Human Life, said the topic has come up only in conversation.

“It’s been discussed in passing, but there has not been opportunity [to propose a bill],” she said. “I think it’s admirable that Mr. Minchew has brought this up, if for no other reason than it’s a conversation that should be had.”

Polling data suggest such a ban would be popular. A 2006 Zogby/Associated Television News poll found that 86 percent of Americans think it should be illegal to abort a fetus on the basis of its sex. Hardly anyone defends the practice, including Minchew’s Democratic opponent in the 10th District, Leesburg Town Council member Dave Butler.

But that hardly means politics surrounding sex-selective abortion are simple.

“It is an interesting proposal, for it confounds the usual left-right divide on this matter,” said James Davison Hunter, professor of religion, culture and social theory at the University of Virginia. “When people do use it [abortion] this way, I gather it is usually to favor male children. The proposal thus presents the challenge to feminists and other progressives to oppose it.”

While abortion-rights supporters do not defend sex-selective abortions, they contend that they happen rarely in the United States. They also say abortion foes are pushing bans to undermine abortion rights in general.

“We know there are millions fewer girls in parts of the world than there should be. That is not the case in America,” said Elizabeth Nash, public policy associate with the Guttmacher Institute, a nonprofit organization focused on sexual and reproductive health.

Some researchers, pointing to skewed sex ratios among the offspring of Asian Americans, say sex-selective abortion is happening in the United States, though certainly not on the scale that it is in China and India.

A 2008 study published in the Proceedings of the National Academy of Sciences concluded that some American parents of Chinese, Korean and Indian descent were using sex-selective abortions to eliminate unwanted daughters. It inferred that from birth data indicating that, after one or two daughters, the probability that the next child would be a boy was unnaturally high.

Abortion-rights groups remain skeptical.

“This is not something we’re seeing in abortion clinics: ‘Oh, I really wanted a boy,’ ” Nash said.

Abdulaziz A. Sachedina, a University of Virginia religion professor known as a leading authority on Islamic biomedical ethics, said two people contemplating sex-selective abortions asked for his advice in the past two years. He dissuaded both, saying, “Just leave it the way God has planned.”

Although he believes the practice is rare, Sachedina said some immigrants might be tempted to use abortion to improve their chances of getting at least one boy and girl, something they could better count on in homelands with traditionally large families.

A ban on sex-selective abortion might be unenforceable and unconstitutional because a woman does not have to provide a reason for an abortion, said Devins, the abortion law expert.

But Lena Edlund, a Columbia University economist involved in the 2008 study, thinks a symbolic gesture would be worthwhile.

“Abortion based on the child’s gender is considered anathema to most Westerners,” she said. “We have not had to really enunciate this because it’s been shared as a core value. We are now in a situation [because of immigration] where it’s not a shared value. . . . It’s not so much whether this can be enforced. I think this is about sending a signal about what society thinks is okay.”

In the Northern Virginia district that Minchew wants to represent in the General Assembly, some experts say a ban could appeal to middle-of-the-road voters: those who believe abortion should be available to someone unprepared to have a child, but not someone who’d simply prefer having one of the opposite sex.

But even Minchew does not appear confident that the ban would have wide appeal in a swing district that covers parts of Loudoun, Frederick and Clarke counties.

He highlighted his opposition to abortion in two mailings, one four pages long, sent over the summer to likely Republican primary voters. In one, he promised to “outlaw ‘sex selection’ abortions.”

“I believe that protecting the life of the innocent may well be the most important function of government — and that includes the unborn,” a mailing read. “Life is a gift from God, and as your Delegate I will do everything I can to protect the life of the unborn.”

Now, before the general election, Minchew is reluctant to discuss abortion generally or sex-selective abortion in particular.

Pressed to elaborate on the sex-selection issue he’d raised in his mailing, Minchew said, “I don’t support the concept of using abortion to determine the sexual makeup of your children.”

“I think Mr. Butler would probably agree,” he added, referring to his Democratic opponent.

Said Butler, “I don’t know anyone who supports abortion for sex selection.”

But Butler is not seconding Minchew’s call for a ban.

Describing his abortion position as “okay with the status quo,” Butler called the sex-selection issue a “red herring.” A ban in Virginia, he said, would probably apply to an “infinitesimal number of people.”

“That’s a problem in China,” Butler said. “I don’t know that it’s a problem at all in Virginia.”