China has 32 million more men under age 20 than women under age 20, and that gap is only expected to increase as parents abort female fetuses to have sons. Chinese parents live under strict birth limits.
Therese Hesketh of University College London, who researched the problem, said that the trend could lead to higher crime rates and other social problems. Her study estimated that China has 119 male births for every 100 female births.
China's population-control laws were put into effect in the 1970s, and the Chinese government says the regulations have prevented an additional 400 million births in a population that is already about 1.3 billion.