Over the last three years, about 163 million Asian girls have been aborted because of their gender, according to a new book by Mara Hvistendahl called "Unnatural Selection: Choosing Boys Over Girls and the Consequences of a World Full of Men."

Selective abortions have led to imbalanced populations in multiple countries.

In China, there are now 113 boys born for every 100 girls and in India, the number is 112 males for every 100 females born, according to the CIA's World Factbook. In some cities in China, the ratio is over 150 boys to every 100 girls. Even places like South Korea, Taiwan, Albania, Azerbaijan and Georgia are seeing a similar phenomenon, Hvistendahl explained in an interview with Macleans, a Canadian-based media outlet, last week.

The normal ratio is 105 boys to every 100 girls, but because of the large population of places like India and China where selective abortions are occurring, the world's birth ratio has now jumped to 107 boys for every 100 girls. explains Jonathan Vast, who wrote a review of "Unnatural Selection" in The Wall Street Journal on Saturday. The U.S. rate is currently 104.7 boys for every 100 girls.

Hvistendahl, who lives in Beijing and writes for Science magazine, described the implication of disproportionate societies. "Historically," she wrote, "societies in which men substantially outnumber women are not nice places to live. Often they are unstable. Sometimes they are violent."

The Atlantic Wire reported a "growing practice of child marriage in China" due to the shortage of women.

BYU professor Valerie Hudson wrote about this same trend in 2004 in her book "Bare Branches: The Security Implication of Asia's Surplus Male Population." Hudson was on 60 Minutes several years ago, predicting an imminent crime culture in China due to the trend, according to an article in the Deseret News.

Last week, one author wrote in the Council on Foreign Relations publication's section that when he went to Tibet several years ago, he was already seeing this. "Unemployed men lounged, drunk, in parks and bus stations. They patrolled the streets and wandered through markets."

In her book, Hvistendahl, a former journalism professor at a university in Shanghai, reports that the practice of male selection has not stopped but rather is spreading. And The Atlantic Wire reported that what really makes this author's research unique is that she in part blames the West for selective abortions.

"Amniocentesis and ultrasound scans have had largely positive applications in the West, where they have been used to detect fetal abnormalities," reported the Guardian on Friday. "But exported to Asia and eastern Europe they have been intricately linked to an explosion of sex selection and a mushrooming of female abortions.

"Hvistendahl claims western governments actively promoted abortion and sex selection in the developing world, encouraging the liberalization of abortion laws and subsidizing sales of ultrasounds as a form of population control."

A Bloomberg News story said that this "availability of ultrasound … together with government efforts to limit a couple's offspring pushed women to avoid multiple births in pursuit of a son."

Her solution: ban the use of ultrasound to find out the gender of a baby in countries where selective abortion is a problem and enforce this ban more thoroughly — including sting operations and further investigations as to why women want to have an abortion. But Vast points out in his review for The Wall Street Journal that China and India already don't allow women to find out the sex of their baby and that these other types of enforcements are too implausible to really happen.

"This is where choice leads," Vast wrote. "This is where choice has already led. Ms. Hvistendahl may wish the matter otherwise, but there are only two alternatives: Restrict abortion or accept the slaughter of millions of baby girls and the calamities that are likely to come with it."

Even Hvistendahl, who Vast says "identifies a ban on abortion — and not the killing of tens of millions of unborn girls — as the 'worst nightmare' of feminism," writes in her book that "after decades of fighting for a woman's right to choose the outcome of her own pregnancy, it is difficult to turn around and point out that women are abusing that right."