China’s population may be smaller than official data suggests, according to a group of researchers, meaning the nation will be replaced by India as the world’s most populous country sooner than expected. It may also mean the problems created by China’s rapidly ageing population and shrinking workforce are more serious than feared, according to the experts. China’s real population may have been about 1.29 billion last year, 90 million fewer people than the official figure released by the National Bureau of Statistics, Yi Fuxian, a researcher at the University of Wisconsin-Madison, said at a symposium at Peking University on Monday. That’s about twice the size of Spain’s population, which is slightly over 46 million. Yi’s research suggested there were 377.6 million new births from 1991 to 2016, less than the official figure of 464.8 million, the South China Morning Post reports.