How much sex selection is there?

I discuss biotechnology and society in my genetics course, and today I wandered across this working paper discussing sex control of offspring, including selective abortion in the US and abroad, preimplantation and prefertilization screening, and possible future effects of the technologies. I'm noting it here because of its inclusion of some numbers:

Even in just the short time that these various methods of sex control have been available, they have had dramatic effects on sex ratios in many parts of the world. Generally, any variation in the sex ratio exceeding 106 boys born per 100 girls born can be assumed to be evidence of sex control. Here are just a few examples of skewed sex ratios around the world today (most recent figures provided). The sex ratio in Venezuela is 107.5, in Yugoslavia 108.6, in Egypt 108.7, in Hong Kong 109.7, in South Korea 110, in Pakistan 110.9, in Delhi, India 117, in China 117, in Cuba 118, in the Caucuses nations of Azerbaijan, Armenia, and Georgia, the sex ratio has reached as high as 120. While the sex ratio in the United States has remained stable at 104.8, certain American ethnic groups have seen a statistically significant rise in their sex ratios. In 1984, the sex ratio for Chinese Americans was 104.6 and for Japanese Americans 102.6; in 2000, these ratios had risen respectively to 107.7 and 106.4 (citation elided).

On the subject of commercial application of sex control technologies, there is this:

Today, sex-control services are openly advertised on the Internet, and sex control could in the future become a big business. Here's how Fortune magazine recently summed up at least the potential market for MicroSort alone: "Each year, some 3.9 million babies are born in the U.S. In surveys, a consistent 25 percent to 35 percent of parents and prospective parents say they would use sex selection if it were available. If just 2 percent of the 25 percent were to use MicroSort, that's 20,000 customers. [and] a $200-million-a-year business in the U.S. alone." (Wadman M, "So you want a girl?" Fortune, Feb. 9, 2001)

And I was actually quite taken by this almost poetic evocation of parenthood:

The salient fact about human procreation in its natural context is that children are not made but begotten. By this we mean that children are the issue of our love, not the product of our wills. A man and a woman do not produce or choose a particular child, as they might buy a particular brand of soap; rather, they stand in relation to their child as recipients of a gift. Gifts and blessings we learn to accept as gratefully as we can; products of our wills we try to shape in accordance with our wants and desires. Procreation as traditionally understood invites acceptance, not reshaping or engineering. It encourages us to see that we do not own our children and that our children exist not simply for our fulfillment. Of course, parents seek to shape and nurture their children in a variety of ways; but being a parent also means being open to the unbidden and unelected in life (emphasis in original).

I think that pretty much sums up my feelings about children.

Yet it is one way of looking at the issue that comes into direct conflict with other cultural forces, such as the intense pressure to have a son, at least for many families. Those pressures differ with different cultural backgrounds, but they are pretty much present at some level everywhere. People's attitudes about biotechnology ultimately reflect deep cultural divisions between different -- sometimes irreconcilible -- goals (via Althouse).

UPDATE: This later post discusses the alternative hypothesis that the elevated male sex ratio in many populations may be explained by hepatitis B infection rates. That hypothesis came after the 2003 working paper discussed in this post, and the issue at present seems to be unresolved.