One of the arguments abortion opponents make, in favor of restricting the procedure, is that parents use it to select the sex of their babies.
Here's Trent Franks, R-Ariz., at a 2011 Congressional hearing, talking about more boy babies being born than girl babies:
"What is causing the skewed ratio: abortion. If the male number in the sex ratio is above 106, it means that couples are having abortions when they find out the mother is carrying a girl." (Franks also has argued against rape and incest exceptions to abortion bans based on the false claim that "the incidence of rape resulting in pregnancy are very low.")
Accusations about sex selection particularly target Asians. "You cannot explain the male to female demographics that are occurring in birth ratios in some ethnic groups here in the United States, and this is widespread, unless you account for sex-selective abortion," said Spencer Cody of South Dakota Right to Life.
This is a conservative talking point that appears to hoist feminists on their own petard. Like other abortion restrictions enacted in the name of women's health and safety, the laws that target sex-selection are designed to take the harsh edge off the anti-abortion movement. It's all about standing up for women and girls.
Franks and Cody have had two data points on their side. One is pretty familiar: In China and India, the sex ratio is in fact skewed in favor of boys.
There is also a study they love to quote, based on U.S. Census data from 2000, which found that after having one or two daughters, foreign-born Chinese, Indian and Korean parents were more likely to become pregnant with a son than the normal statistics would bear.
There was no skewing of sex ratios at birth -- just at conception. Which doesn't implicate abortion.
Still, in reaction to the conservative campaign, eight states have banned abortion for purposes of sex selection. Illinois and Pennsylvania were the first to go down this road, in the 1980s, and six other states have followed them in the last four years. The rest of the list is Arizona, Kansas, North Carolina, North Dakota, South Dakota and Oklahoma.
South Dakota goes so far as to require doctors to ask women seeking abortion if they know the sex of the "unborn child" and are having an abortion because of it. In Oklahoma, your husband or parent or sibling can sue you if you have an abortion for this reason.
Last week, the International Human Rights Clinic of the University of Chicago Law School and the National Asian Pacific American Women's Forum published a new study that exposes banning abortion based on sex-selection for what it is: a way to restrict abortion, not to combat gender discrimination.
The study looks at a large and recent data set (called the American Community Survey) and concludes that foreign-born Asian-Americans and Indians don't have birth rates that skew toward boys. Actually, "Asian Americans have more girls than white Americans." So much for a "widespread" suspect ethnic practice.
More truth-busting bits from the study: India and China aren't the worst places in the world for skewed sex ratios at birth. That distinction goes to Liechtenstein and Armenia, followed by Hong Kong and Azerbaijan.
Also, after Illinois and Pennsylvania banned abortion for sex-selection in 1984 and 1989, the ratios of boy to girl babies didn't change -- in other words, the law had none of the effect for which it was supposedly intended.
This really should come as no surprise. If you want to control the sex of your child, the easiest way to go is a method called sperm sorting. If legislators really cared about preventing this, that's what they'd try to ban.
And yet, as Slate's Hanna Rosin pointed out a few years ago, American parents who turn to sperm sorting increasingly are trying to have ... girls.
"A newer method for sperm selection, called MicroSort, is currently completing Food and Drug Administration clinical trials," she wrote in the Atlantic. "The girl requests for that method run at about 75 percent."
In Liechtenstein, Armenia, Hong Kong, Azerbaijan, China and India, the problem of parental preference for boys is a real one. But in the United States, it's a canard. And there is nothing feminist about invoking it to make abortions harder to get.
Emily Bazelon, is a Slate senior editor and a fellow at Yale Law School. She is the author of "Sticks and Stones."