More than 24 million Chinese men of marrying age could find themselves without spouses in 2020, state media reported on Monday, citing sex-specific abortions as a major contributing factor.
The study, by the government-backed Chinese Academy of Social Sciences, named the gender imbalance among newborns as the most serious demographic problem for the country's population of 1.3 billion, the Global Times said.
"Sex-specific abortions remained extremely commonplace, especially in rural areas," where the cultural preference for boys over girls is strongest, the study said while noting the reasons for the gender imbalance were "complex".
Researcher Wang Guangzhou said the skewed birth ratio could lead to difficulties for men with lower incomes in finding spouses, as well as a widening age gap between partners.
Another researcher quoted by the newspaper, Wang Yuesheng, said men in poorer parts of China would be forced to accept marriages late in life or remain single forever, which could "cause a break in family lines".
"The chance of getting married will be rare if a man is more than 40 years old in the countryside. They will be more dependent on social security as they age and have fewer household resources to rely on," Wang said.
The paper said abductions and trafficking of women were "rampant" in areas with excess numbers of men, citing the National Population and Family Planning Commission.
Illegal marriages and forced prostitution were also problems in those areas, it said.
Authorities put the normal male-female ratio at between 103-107 males for every 100 females. In 2005, the last year for which data was made available, there were 119 boys for every 100 girls, the report said.
China first implemented its "one-child" population control policy in 1979.
Researchers said the gender imbalance problem cropped up in the late 1980s when women were first commonly able to find out the sex of their foetuses, leading to an increased number of sex-selective abortions.