Researchers may have found millions of women and girls who were believed to be missing across China.
It was estimated that between 30 and 60 million girls were "missing" in the world's most populous country, with many believing they were either killed before or after birth simply because of their gender.
But new research suggests 25 million girls do actually exist after all and didn't appear on government records because they simply weren't registered.
The findings raise the possibility that the country's serious gender imbalance is not as severe as previously believed.
John Kennedy, an associate professor of political science at the University of Kansas, along with co-author Shi Yaojiang, an economics professor at Shaanxi Normal University, believe these girls went unreported at birth.
However they later appeared on government census records.
Prof Kennedy said it now appeared the administrative story had to do with how births are registered at local levels in China.
"People think 30 million girls are missing from the population. That's the population of California, and they think they're just gone," he said on the university's website.
"Most people are using a demographic explanation to say that abortion or infanticide are the reasons they don't show up in the census and that they don't exist. But we find there is a political explanation."
The sex ratio at birth was 118 males for every 100 females the 2010 Chinese census found.
However according to the new research, published this month in the journal China Quarterly, the female to male ratio isn't as dire as it sounds.
Using interviews and observations with villagers in rural China, the researchers analysed national population data which spanned a 25-year period.
They found a combination of late registration and unreported births helped explain a larger portion of the "missing girls" than previously cited in Chinese sex-ratio-at-birth statistics.
Prof Kennedy, who began looking into this issue 20 years ago, said they found authorities, particularly in rural areas, would turn a blind eye to extra children as they had to work and live in the village where such policies were implemented.
One farmer he spoke at this time called his second daughter "the non-existent one". In the 1980s rural Chinese were allowed to have a second child if their first was a girl.
The farmer, from the northern Shaanxi province, had a third child, a boy, and registered his son instead as his second child.
Researchers also found girls such as this were often reported later in life, often from the age of 10.
They then compared the number of children born in 1990 and compared it with the population figures 20 years later, discovering an extra four million people, with a million more females than males.
"If we go over a course of 25 years, it's possible there are about 25 million women in the statistics that weren't there at birth," Prof Kennedy said.
Last year, Beijing announced it was officially ending the one child policy after a bill was signed off allowing all married couples to have a second child.
The policy was introduced in the 1979 by then Chinese leader Deng Xiaoping in a bid to curb China's rapidly growing population.
But the one-child policy meant couples faced severe penalties, including fines and reported forced abortions if they had further pregnancies and children.
Concerns were also raised about the gender imbalance given the societal preference for boys while claims of sex-selective abortions or infanticide targeting girls also emerged.
The policy was loosened for rural families and ethnic minorities as concerns were filed over an ageing population and a perceived gender imbalance.
Further reforms occurred in 2013 when the government allowed couples to have a second child if they were only children themselves, however this did little to appease the problem with too few people taking the opportunity, AFP reported.
Some critics claimed it was too little too late to address the looming population crisis.