HVISTENDAHL: It was understood largely as a local issue. In China it was blamed on the one-child policy, and the pressure on women to have sons, and in India it was explained as a function of dowry, of daughters being expensive....And then they were positioned within the broader context of gender discrimination, so you’d see reports saying “Oh, people have had this preference for sons for hundreds of thousands of years.”

HVISTENDAHL: Yes. It was when they broke it down by province. I saw that in western China you don’t have it so much, but in smaller booming cities in the East, between Shanghai and Beijing, the sex ratio is really high. In some places, it’s two boys for every girl.

HVISTENDAHL: Sex selection is happening in China, India, South Korea, Taiwan, Vietnam, Albania, Azerbaijan, Georgia. These are all places where economic development has hit recently, and people are having fewer children and trying to make sure that one is a boy.

Based on conversations held everywhere from Albania to Vietnam, with doctors, prospective parents, demographers, activists, and mail-order brides from Albania to Vietnam, Hvistendahl found that sex selection is linked to rapidly growing economies, the dispersal of cheap, portable prenatal screening technology, and holdover from midcentury Western population-control initiatives. More surprisingly, she discovered that as fewer girls are born, it does little to improve their status, and in fact makes them targets for arranged or forced marriages, kidnapping, and sex work.

In a new book, “Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of Men,” American journalist Mara Hvistendahl explores how birth ratios got out of hand and looks into the actual and potential effects on the women, men, and social economies of these regions. While for years the myth has held that any choice of sons occurred through rural infanticide, sex selection turns out to proliferate in the middle and upper classes; parents who have access to obstetric services, ultrasound, and abortion are the ones likely to choose boys.

Over the past few decades, 160 million women have vanished from East and South Asia — or, to be more accurate, they were never born at all. Throughout the region, the practice of sex selection — prenatal sex screening followed by selective termination of pregnancies — has yielded a generation packed with boys. From a normal level of 105 boys to 100 girls, the ratio has shifted to 120, 150, and, in some cases, nearly 200 boys born for every 100 girls. In some countries, like South Korea, ratios spiked and are now returning to normal. But sex selection is on the rise in Eastern Europe, Southeast Asia, and the Middle East.

IDEAS: How did modern sex selection begin to take hold in Asia?

HVISTENDAHL: In the 1960s and ’70s population growth was a huge issue, maybe like climate change today. The concern was genuine, but, unfortunately, in searching for ways to solve the problem, population control organizations came up with all sorts of wild solutions. It turned out to be a pretty dark period for reproductive rights. In the ’70s, 6 million men were sterilized in India, some of them forced. When the president of the Population Council wrote an article for Science in, I think, 1969, he ranked the various methods and ranked sex selection as having a high moral value. Sex selection emerged as a method that would be voluntary, and one that would appeal to those in the developing world, as most couples in those places would keep having children until they had a boy.

IDEAS: You also connect this trend to an increase in wealth. As people have more money, they have fewer children, but want those they have to be their preference.

HVISTENDAHL: There is a myth that this is something that poor women do, but if you look at the numbers, and where sex selection is first used, it happens among the upper classes....The scary thing is that in many countries it’s still with the elite, and so we’ll have another wave as the rest of society begins to use it.

IDEAS: And because sex selection costs money, it becomes a kind of consumer good.

HVISTENDAHL: There were many doctors who raised that point. Definitely there are people making money off of sex selections. Doctors are making money. GE, which produces low-cost ultrasound machines for the Asian market, is making money off it. They have reformed their practices after lobbying from activists in India, but they’re still there, marketing and introducing new models....I wouldn’t say that patients are the only ones driving it.

IDEAS: You’d think that as women became rarer, they’d be more in demand and thus more powerful — but you haven’t found that to be true.

HVISTENDAHL: Economists initially did propose that the supply of women would go down and they would become more valuable to society, [as] in a typical supply and demand relationship. And that has happened, but in a really crude way. The price does go up, but in many parts of Asia women don’t control that value. That value appears when you kidnap her and sell her into marriage. Some of the marriage migration is voluntary, like that out of Vietnam for South Korean and Taiwanese husbands. But there are other cases where women are being kidnapped, and girls trafficked. So it’s amazing to me that people persist in saying that women’s status has improved as a result of this shift. Nobody in Asia, certainly, believes that.

IDEAS: Is there activism cropping up to respond to this?

HVISTENDAHL: In China, a lot of smaller local organizations are doing very good work, providing support to forced brides who find themselves in abusive marriages. There are loads of Indian organizations working on it, too. The issue is that they need international support.

IDEAS: What about responses from governments?

HVISTENDAHL: There have been programs encouraging parents in India and China to have girls, and they range from paying people to providing other incentives to cracking down on sex selections. The thing is, it’s not priority number one. Economic growth seems to be the main priority.

IDEAS: What is the future for these societies with many more men than women?

HVISTENDAHL: There’s evidence that crime rates, and particularly sex crimes, have increased in northwest India and eastern China, places where the birth ratios are way off. History is an imperfect guide, but if you look at societies where men significantly outnumbered women, they tended to have a lot of serious problems. And it’s certainly true there will be a lot of men who have trouble finding women.

I don’t think that the reason we should care about sex selection is that it could be a security threat; it’s that it’s having tremendous effect on societies. By being aware of the prominence of sex selection, we can hope to reduce its impact. It went essentially ignored in Asia and South Asia for years. Now, in countries newly taking to this practice, in Azerbaijan, Albania, and Georgia, the effects are at least being caught earlier.

J. Gabriel Boylan is an assistant editor of Harper’s Magazine.

© Copyright 2011 Globe Newspaper Company.