(January 2012) Dudley Poston is fascinated by China's "demographic exceptionalism." The country has the world's largest population, and in the 70s managed to achieve one of the fastest fertility declines in human history. China's "one-child" population policy has resulted in a number of unique demographic events and transitions, including an imbalance of the sex ratio at birth. Millions of "extra" boys have been born: Already, 41 million bachelors will not have women to marry. If nothing is done to change this trend, Poston noted, by 2020 there will be 55 million extra boys in China.

As part of PRB's 2011-2012 Policy Seminar series, Poston discussed China's fertility control policies. He is a professor of sociology and director of the Asian Studies Program at Texas A&M University.

China's fertility control policies began in 1971, at the same time the country was undergoing rapid socioeconomic change. The "later, longer, fewer" campaign promoted two-child families, rewarding those who complied and penalizing those who did not. As a result, China's total fertility rate plummeted, from six children per woman in 1970 to less than three children in 1979.

So why did China implement a one-child policy if the fertility rate had been so successfully reduced? Poston said that China didn't know much about demography in the early 1970s, but by 1979, "they knew that even though they had dropped their fertility down to three, the momentum from these high-fertility years was going to continue for the country to grow."

During this time, China also dominated the world in manufacturing goods, Poston said. He added quickly, "at the same time in the seventies, there was remarkable socioeconomic development. And knowing what all of us know about demographic transition theory, that's really part of the reason for fertility reduction: modernization and socioeconomic development."

Poston said that the sex ratio at birth in several countries today is out of balance, due to four factors: rapid fertility transition, son preference, available technology to determine the sex of the fetus, and physical and cultural ease of access to abortion. The rapid pace of fertility transition has given China little time to change a cultural norm of favoring sons. And prenatal sex identification via sonar technology, followed by female-specific abortion, is thought by demographers to be the most likely reason for China's higher-than-biologically normal sex ratio at birth.

A sex ratio at birth of 105 males for every 100 females is average. There are slight differences in trends and patterns, by year, by age of mother, live birth order, and race/ethnicity of the mother. "The reason you need 105 boys—and this is perhaps a demographic universal—is because of the longevity, the survival advantage that women have," he said. "So by the time they marry, there's a balance." The sex ratio at birth in China is 120 males per 100 females.

Poston and his colleagues produced estimates of the number of excess males by applying survival probabilities from China life tables to actual numbers of males and females born every year from 1983 through 2010.  Males are survived to age 25 and females are survived to age 23 because these are typical ages for first marriage in China. The difference between the number of 25-year-old males and the number of 23-year-old females in any given year represents the number of excess males or bachelors. Poston's research finds that between 1983 and 2010, the imbalanced sex ratio at birth in China has resulted in a surplus of 40 million males who will be unable to find appropriately aged Chinese women to marry.1

China has begun a new national campaign to crack down on the use of technology to determine the sex of a fetus for anything other than medical purposes, and on sex-selective abortions. The National Population and Family Planning Commission, the Ministry of Health, and other government agencies will enforce the campaign and make sure health institutions are better-supervised, Poston said.

In the meantime, the reality of millions of excess males remains a problem. "These extra men will be the bottom of the barrel, the rural boys that nobody wants, and they won't have any money," Poston said, so he believes that increased prostitution, an unprecedented spread of HIV, and the proliferation of bachelor ghettos are much more likely than an influx of foreign brides or sudden increased homosexuality as a result of this gender imbalance.

"China's concentrated HIV epidemic is on the brink of becoming a generalized one," Poston warned. Also a factor are the roughly 200 million floating migrants who move from rural China to urban areas in search of work. The number of HIV cases in China in the next decade and later, owing to bachelors and floaters, could well rival the numbers in sub-Saharan Africa: 23 million adults and children infected as of 2007 (according to UNAIDS).

Tyjen Tsai is a writer/editor at PRB.


  1. Dudley L. Poston Jr., Eugenia Conde, and Bethany DeSalvo, "China's Unbalanced Sex Ratio at Birth, Millions of Excess Bachelors and Societal Implications," Vulnerable Children and Youth Studies 6, no. 4 (2011): 314-20.